GB2461962A - NMDA receptor antagonists for the treatment of ear disorders - Google Patents

Abstract

A sterile, pH balanced, endotoxin free pharmaceutical composition for the treatment of otic disease comprises an NMDA receptor antagonist in the form of microparticles. Preferably the antagonist is an acrylcyclokylamine, a chinazoline, ketamine, a NR2B9c fusion peptide or 7-CK. Methods of treatment by administration of the NMDA receptor antagonist to the inner ear are disclosed.

Description

METHODS FOR THE TREATMENT OF OTIC DISORDERS COMPRISING GLUTAMATE AGONISTS

AND ANTAGONISTS

100011 This patent application claims the benefit of U.S. Provisional Application Ser. No. 61/083,830, filed July 25, 2008; U.S. Provisional Application Ser. No. 61/086,094, filed August 04, 2008; U.S. Provisional Application Ser. No. 61/160,233, filed March 13, 2009; and U.S. Provisional Application Ser. No. 61/164,812, filed March 30, 2009 all of which are herein incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

100021 Vertebrates have a pair of ears, placed symmetrically on opposite sides of the head. The ear serves as both the sense organ that detects sound and the organ that maintains balance and body position. The ear is generally divided into three portions: the outer ear, auris media (or middle ear) and the auris interna (or inner ear).

SUMMARY OF THE INVENTION

100031 Disclosed herein, in certain embodiments, is a pharmaceutical composition for use in the treatment of a disease of the ear characterized by the dysfunction of an NMDA receptor, comprising: (a) an NMDA receptor antagonist in the form of microparticulates; and (b) sterile water, q.s., buffered to provide a perilymph-suitable pH between about 7.0 and about 7.6; and having: (a) less than about 50 colony forming units (cfu) of microbiological agents per gram of composition; and (b) less than about 5 EU/kg composition. In some embodiments, the NMDA receptor antagonist is at least one of: an arylcycloalkylamine and a chinazoline. In some embodiments, the NMDA receptor antagonist is at least one of: (5)-ketamine, a salt of (s)-ketamine, 7-CK, and a salt of 7-CK. In some embodiments, the NMDA receptor antagonist is a fusion peptide comprising (a) a transporter peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins. In some embodiments, the NMDA receptor antagonist is released in a therapeutically effective amount from the composition for a period of at least 4 days. In some embodiments, the composition is a thermoreversible gel. In some embodiments, the composition further comprises a penetration enhancer. In some embodiments, the composition further comprises a round window membrane mucoadhesive. In some embodiments, the NMDA receptor antagonist is essentially in the form of micronized particles. In some embodiments, the practical osmolarity is from about 250 to about 320 mM.

100041 Disclosed herein, in certain embodiments, is a pharmaceutical composition for use in the treatment of a disease of the ear characterized by the dysfunction of an NMDA receptor, comprising: (a) an active agent selected from at least one of (5)-ketamine, salts of (5)-ketamine, 7-CK, salts of 7-CK, and a fusion peptide comprising (a) a transporter peptide and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins in the form of microparticulates; and (b) sterile water, q.s., buffered to provide a perilymph-suitable pH between about 7.0 and about 7.6; and having: (a) less than about 50 colony forming units (cfu) of microbiological agents per gram of composition; and (b) less than about 5 EU/kg composition. In some embodiments, the active agent is released from the composition in a therapeutically-effective amount for a period of at least 4 days. In some embodiments, the composition is a thermoreversible gel. In some embodiments, the composition further comprises a penetration enhancer. In some embodiments, the composition further comprises a round window membrane mucoadhesive. In some embodiments, the active agent is essentially in the form of micronized particles. In some embodiments, the practical osmolarity is from about 250 to about 320 mM.

100051 Disclosed herein, in certain embodiments, is a method of treating a disease of the ear characterized by the dysfunction of an NMDA receptor, comprising administering to an individual in need thereof a composition comprising: (a) an NMDA receptor antagonist in the form of microparticulates; and (b) sterile water, q.s., buffered to provide a perilymph-suitable pH between about 7.0 and about 7.6; and having: (a) less than about 50 colony forming units (cfu) of microbiological agents per gram of composition; and (b) less than about 5 EU/kg composition. In some embodiments, the NMDA receptor antagonist is at least one of: an arylcycloalkylamine and a chinazoline. In some embodiments, the NMDA receptor antagonist is at least one of: (S)-ketamine, a salt of (s)-ketamine, 7-CK, and a salt of 7-CK. In some embodiments, the NMDA receptor antagonist is a fusion peptide comprising (a) a transporter peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins. In some embodiments, the NMDA receptor antagonist is released from the composition in a therapeutically-effective amount for a period of at least 4 days. In some embodiments, the composition is administered across the round window. In some embodiments, the NMDA receptor antagonist is essentially in the form of micronized particles. In some embodiments, the practical osmolarity is from about 250 to about 320 mM.

100061 Disclosed herein, in certain embodiments, is a method of treating a disease of the ear characterized by the dysfunction of an NMDA receptor, comprising administering to an individual in need thereof a composition comprising: (a) an active agent selected from at least one of (S)-ketamine, salts of (S)-ketamine, 7-CK, salts of 7-CK, and a fusion peptide comprising (a) a transporter peptide and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins in the form of microparticulates; and (b) sterile water, q.s., buffered to provide a perilymph-suitable pH between about 7.0 and about 7.6; and having: (a) less than about 50 colony forming units (cfu) of microbiological agents per gram of composition; (b) less than about 5 EU/kg composition. In some embodiments, the active agent is at least one of: an arylcycloalkylamine and a chinazoline.

In some embodiments, the active agent is at least one of: (S)-ketamine, a salt of(s)-ketamine, 7-CK, and a salt of 7-CK. In some embodiments, the active agent is a fusion peptide comprising (a) a transporter peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins. In some embodiments, the active agent is released from the composition in a therpaeutically-effective amount for a period of at least 4 days. In some embodiments, the composition is administered across the round window. In some embodiments, the active agent is essentially in the form of micronized particles. In some embodiments, the practical osmolarity is from about 250 to about 320 mJVI.

DETAILED DESCRIPTION OF THE INVENTION

100071 Disclosed herein, in certain embodiments, is a method of treating an otic disorder characterized by the dysfunction of an NMDA receptor. In some embodiments, a disease of the ear characterized by dysfunction of an NMDA receptor is selected from at least one of tinnitus and excitotoxicity.

100081 A few systemically-delivered (oral, intravenous, and/or intramuscular) NMDA receptor antagonists/formulations are available for the treatment of these otic disorders. However, systemic drug administration results in the NMDA receptor antagonist having potentially harmful (and non-therapeutically-relevant) levels in the serum, and lower levels at the target auris media and auris interna organ structures. Due to this inequality, fairly large amounts of drug are required to deliver sufficient, therapeutically effective quantities to the inner ear. Further, in certain instances, the high serum amounts required to effectuate sufficient delivery to the target site result in systemic toxicities and adverse side effects. In some instances, systemic toxicities occur as a result of liver breakdown and processing of an NMDA receptor antagonist, forming toxic metabolites that effectively erase any benefit attained from the administered therapeutic.

100091 To overcome these limitations, disclosed herein are compositions and methods for local delivery of NMDA receptor antagonists to targeted auris structures of the inner ear. Access to, for example, the vestibular and cochlear apparatus will occur through the tympanic membrane, and the auris media including round window membrane, the oval window/stapes footplate, the annular ligament and through the otic capsule/temporal bone.

By specifically targeting an auris structure, adverse side effects as a result of systemic treatment are avoided.

100101 However, intra-tympanic injections create several unrecognized problems such as changing the osmolarity and pH of the perilymph and endolymph, and introducing pathogens and endotoxins that directly or indirectly damage inner ear structures. One of the reasons the art may not have recognized these problems is that there are no approved intra-tympanic compositions: the inner ear provides sui generis formulation challenges.

Thus, compositions developed for other parts of the body have little to no relevance for an intra-tympanic composition.

100111 U.S. Application Publication Nos. 2006/0063802 and 2005/0214338 disclose compositions for local administration to the inner ear. There is no disclosure of osmolarity or pH requirements, or sterility requirements for the compositions. WO 2007/03 8949 discloses compositions for the treatment of inner ear disorders. No guidance is provided on pyrogenicity or sterility requirements.

100121 Fernandez et al. Biomaterials, 26: 3311-3318 (2005) describes compositions useful to treat inner ear disease. Fernandez et al. do not disclose osmolarity, pyrogenicity, pH, or sterility levels of the compositions described therein. Paulson et al., The Laryngoscope, 118: 706 (2008) describe sustained release compositions useful in treatment of inner ear diseases. Again, Paulson et al do not disclose osmolarity, pyrogenicity, pH, or sterility parameters or requirements for the compositions described therein.

100131 C. Gang, et al., J. Sichuan Univ. 37:456-459 (2006) describe compositions for the treatment of inner ear disease. The formulation described in Gang, et al. is sterilized under conditions that lead to breakdown of the active agent. There is no disclosure regarding osmolarity, pyrogenicity, pH, or sterility parameters or requirements for the compositions described therein.

100141 Feng et al., Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi 42:443-6 (June 2007) and Feng et al., Zhonghua YiXue Za Zhi 87:2289-9 1 (August 2007) describe how compositions comprising 20% and 25% poloxamer 407. There is no active agent in the solutions described therein, and there is no disclosure regarding osmolarity, pyrogenicity, pH, or sterility parameters or requirements for the solutions described therein.

Solutions 100151 Intra-tympanic injections result in an imbalance in the pH and/or osmolarity of the endolymph and/or perilymph. Imbalances in the pH and osmolarity of inner ear fluids disrupt hearing. To overcome these problems, disclosed herein are compositions for delivery to the inner ear wherein the pH and osmolarity of the compositions are adjusted for compatibility with the inner ear.

100161 Additionally, intra-tympanic injections introduce foreign matter into a previously closed system. As such, intra-tympanic injections have a high risk of introducing pathogens and/or endotoxins into the inner ear. In certain instances, the presence of pathogens in the inner ear results in multiple disorders (e.g., labyrinthitis), and the disruption of the pH and osmolarity of inner ear fluids. In certain instances, the latter results in hearing loss and disequilibrium. Microbial infections of the inner ear are extremely hard to treat due to multiple physiological barriers (e.g., the blood-labyrinth barrier, the blood-perilymph barrier, and the blood-endolymph barrier).

Furthermore, immune responses are themselves extremely detrimental to the inner ear. In certain instances, the initiation and prolonged occurrence of an immune response in the inner ear results in autoimmune sensorineural hearing loss, systemic autoimmune disorders, ossification of inner ear structures, degeneration of the organ of Corti, degeneration of the stria vascularis, degeneration of the spiral ganglion, and disequilibrium. To avoid the highly detrimental effects of the introduction of pathogens and the induction of an immune response, disclosed herein are compositions with stringent sterility requirements.

Certain Definitions 100171 The term "glutamate receptor antagonist" means a compound that interferes with or inhibits the activity of a glutamate receptor. In some embodiments, the receptor is an AMPA receptor, or NMDA receptor. In some embodiments, a glutamate receptor antagonist binds to a glutamate receptor but said binding does not produce a physiological response. Glutamate receptor antagonists include partial agonists, inverse agonists, neutral or competitive antagonists, allosteric antagonists, and/or orthosteric antagonists.

100181 The term "glutamate receptor agonist" means a compound that binds to a glutamate receptor and activates the receptor. The term further includes a compound that facilitates the binding of a native ligand. In some embodiments, the receptor is an mGlu receptor. Glutamate receptor agonists include partial antagonists, allosteric agonists, and/or orthosteric agonists.

100191 The term "auris-acceptable" with respect to a formulation, composition or ingredient, as used herein, includes having no persistent detrimental effect on the auris media (or middle ear) and the auris interna (or inner ear) of the subject being treated. By "auris-pharmaceutically acceptable," as used herein, refers to a material, such as a carrier or diluent, which does not abrogate the biological activity or properties of the compound in reference to the auris media (or middle ear) and the auris interna (or inner ear), and is relatively or is reduced in toxicity to the auris media (or middle ear) and the auris interna (or inner ear), i.e., the material is administered to an individual without causing undesirable biological effects or interacting in a deleterious manner with any of the components of the composition in which it is contained.

100201 As used herein, amelioration or lessening of the symptoms of a particular otic disease, disorder or condition by administration of a particular compound or pharmaceutical composition refers to any decrease of severity, delay in onset, slowing of progression, or shortening of duration, whether permanent or temporary, lasting or transient that is attributed to or associated with administration of the compound or composition.

100211 "Auris interna" refers to the inner ear, including the cochlea and the vestibular labyrinth, and the round window that connects the cochlea with the middle ear.

100221 "Auris-bioavailability" or "Auris-interna bioavailability" or "Auris-media bioavailability" or "Auris-extema bioavailability" refers to the percentage of the administered dose of compounds disclosed herein that becomes available in the targeted auris structure of the animal or human being studied.

100231 "Auris media" refers to the middle ear, including the tympanic cavity, auditory ossicles and oval window, which connects the middle ear with the inner ear.

100241 "Auris externa" refers to the outer ear, including the pinna, the auditory canal, and the tympanic membrane, which connects the outer ear with the middle ear.

100251 "Carrier materials" are excipients that are compatible with an active agent disclosed herein, the targeted auris structure(s) and the release profile properties of the auris-acceptable pharmaceutical formulations. Such carrier materials include, e.g., binders, suspending agents, disintegration agents, filling agents, surfactants, solubilizers, stabilizers, lubricants, wetting agents, diluents, and the like. "Auris-pharmaceutically compatible carrier materials" include, but are not limited to, acacia, gelatin, colloidal silicon dioxide, calcium glycerophosphate, calcium lactate, maltodextrin, glycerine, magnesium silicate, polyvinylpyrrolidone (PVP), cholesterol, cholesterol esters, sodium caseinate, soy lecithin, taurocholic acid, phosphatidyicholine, sodium chloride, tricalcium phosphate, dipotassium phosphate, cellulose and cellulose conjugates, sugars sodium stearoyl lactylate, carrageenan, monoglyceride, diglyceride, pregelatinized starch, and the like.

100261 The term "diluent" refers to chemical compounds that are used to dilute an active agent disclosed herein prior to delivery and which are compatible with the targeted auris structure(s).

100271 "Dispersing agents," and/or "viscosity modulating agents" are materials that control the diffusion and homogeneity of an active agent disclosed herein through liquid media. Examples of diffusion facilitators/dispersing agents include but are not limited to hydrophilic polymers, electrolytes, Tween� 60 or 80, PEG, polyvinylpyrrolidone (PVP; commercially known as Plasdone�), and the carbohydrate-based dispersing agents such as, for example, hydroxypropyl celluloses (e.g., HPC, HPC-SL, and HPC-L), hydroxypropyl methylcelluloses (e.g., HPMC K100, HPMC K4M, HPMC K15M, and HPMC K100M), carboxymethylcellulose sodium, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose phthalate, hydroxypropylmethylcellulose acetate stearate (HPMCAS), noncrystalline cellulose, magnesium aluminum silicate, triethanolamine, polyvinyl alcohol (PVA), vinyl pyrrolidone/vinyl acetate copolymer (S630), 4-( 1,1,3,3 -tetramethylbutyl)-phenol polymer with ethylene oxide and formaldehyde (also known as tyloxapol), poloxamers (e.g., Pluronics F68�, F88�, and F108�, which are block copolymers of ethylene oxide and propylene oxide); and poloxamines (e.g., Tetronic 908�, also known as Poloxamine 908�, which is a tetrafunctional block copolymer derived from sequential addition of propylene oxide and ethylene oxide to ethylenediamine (BASF Corporation, Parsippany, N.J.)), polyvinylpyrrolidone Ki 2, polyvinylpyrrolidone Ki 7, polyvinylpyrrolidone K25, or polyvinylpyrrolidone K3 0, polyvinylpyrrolidone/vinyl acetate copolymer (S-630), polyethylene glycol, e.g., the polyethylene glycol has a molecular weight of about 300 to about 6000, or about 3350 to about 4000, or about 7000 to about 5400, sodium carboxymethylcellulose, methylcellulose, polysorbate- 80, sodium alginate, gums, such as, e.g., gum tragacanth and gum acacia, guar gum, xanthans, including xanthan gum, sugars, cellulosics, such as, e.g., sodium carboxymethylcellulose, methylcellulose, sodium carboxymethylcellulose, polysorbate-80, sodium alginate, polyethoxylated sorbitan monolaurate, polyethoxylated sorbitan monolaurate, povidone, carbomers, polyvinyl alcohol (PVA), alginates, chitosans and combinations thereof. Plasticizers such as cellulose or triethyl cellulose are also be used as dispersing agents. Optional dispersing agents useful in liposomal dispersions and self-emulsifying dispersions of an active agent disclosed herein disclosed herein are dimyristoyl phosphatidyl choline, natural phosphatidyl choline from eggs, natural phosphatidyl glycerol from eggs, cholesterol and isopropyl myristate.

100281 "Drug absorption" or "absorption" refers to the process of movement of an active agent disclosed herein from the localized site of administration, by way of example only, the round window membrane of the inner ear, and across a barrier (the round window membranes, as described below) into the auris interna or inner ear structures.

100291 The terms "co-administration" or the like, as used herein, are meant to encompass administration of an active agent disclosed herein to a single patient, and are intended to include treatment regimens in which an active agent disclosed herein are administered by the same or different route of administration or at the same or different time.

100301 The terms "effective amount" or "therapeutically effective amount," as used herein, refer to a sufficient amount of a active agent disclosed herein being administered that would be expected to relieve to some extent one or more of the symptoms of the disease or condition being treated. For example, an "effective amount" for therapeutic uses is the amount of an active agent disclosed herein required to provide a decrease or amelioration in disease symptoms without undue adverse side effects. The term "therapeutically effective amount" includes, for example, a prophylactically effective amount. An "effective amount" of a composition disclosed herein is an amount effective to achieve a desired pharmacologic effect or therapeutic improvement without undue adverse side effects. It is understood that "an effective amount" or "a therapeutically effective amount" varies, in some embodiments, from subject to subject, due to variation in metabolism of the compound administered, age, weight, general condition of the subject, the condition being treated, the severity of the condition being treated, and the judgment of the prescribing physician. It is also understood that "an effective amount" in an extended-release dosing format may differ from "an effective amount" in an immediate-release dosing format based upon pharmacokinetic and pharmacodynamic considerations.

100311 The terms "enhance" or "enhancing" refers to an increase or prolongation of either the potency or duration of a desired effect of an active agent disclosed herein, or a diminution of any adverse symptom such as localized pain that is consequent upon administration of the therapeutic agent. Thus, in regard to enhancing the effect of an active agent disclosed herein, the term "enhancing" refers to the ability to increase or prolong, either in potency or duration, the effect of other therapeutic agents that are used in combination with an active agent disclosed herein. An "enhancing-effective amount," as used herein, refers to an amount of an active agent disclosed herein, or other therapeutic agent, that is adequate to enhance the effect an active agent disclosed herein in a desired system. When used in a patient, amounts effective for this use will depend on the severity and course of the disease, disorder or condition, previous therapy, the patient's health status and response to the drugs, and the judgment of the treating physician.

100321 The term "inhibiting" includes preventing, slowing, or reversing the development of a condition, for example, ototoxicity, or advancement of a condition in a patient necessitating treatment.

100331 "Round window membrane" is the membrane in humans that covers the fenestrae cochlea (also known as the circular window, fenestrae rotunda, or round window). In humans, the thickness of round window membrane is about 70 micron.

100341 "Solubilizers" refers to auris-acceptable compounds such as triacetin, triethylcitrate, ethyl oleate, ethyl caprylate, sodium lauryl sulfate, sodium doccusate, vitamin E TPGS, dimethylacetamide, N-methylpyrrolidone, N-hydroxyethylpynolidone, polyvinylpyrrolidone, hydroxypropylmethyl cellulose, hydroxypropyl cyclodextrins, ethanol, n-butanol, isopropyl alcohol, cholesterol, bile salts, polyethylene glycol 200-600, glycofurol, transcutol, propylene glycol, and dimethyl isosorbide and the like.

100351 "Stabilizers" refers to compounds such as any antioxidation agents, buffers, acids, preservatives and the like that are compatible with the environment of the targeted auris structure. Stabilizers include but are not limited to agents that will do any of (1) improve the compatibility of excipients with a container, or a delivery system, including a syringe or a glass bottle, (2) improve the stability of a component of the composition, or (3) improve formulation stability.

100361 The terms "subject," "patient" and "individual" are used interchangeably. As used herein, the terms mean an animal, preferably a mammal, including a human or non-human. The terms are not to be construed as requiring the supervision of a medical professional (e.g., a physician, nurse, physician's assistant, hospice worker, or orderly).

100371 "Surfactants" refers to compounds that are auris-acceptable, such as sodium lauryl sulfate, sodium docusate, Tween� 60 or 80, triacetin, vitamin E TPGS, sorbitan monooleate, polyoxyethylene sorbitan monooleate, polysorbates, polaxomers, bile salts, glyceryl monostearate, copolymers of ethylene oxide and propylene oxide, e.g., Pluronic� (BASF), and the like. Some other surfactants include polyoxyethylene fatty acid glycerides and vegetable oils, e.g., polyoxyethylene (60) hydrogenated castor oil; and polyoxyethylene alkylethers and alkylphenyl ethers, e.g., octoxynol 10, octoxynol 40. In some embodiments, surfactants are included to enhance physical stability or for other purposes.

100381 The terms "treat," "treating" or "treatment," as used herein, include alleviating, abating or ameliorating a disease or condition symptoms, preventing additional symptoms, ameliorating or preventing the underlying metabolic causes of symptoms, inhibiting the disease or condition, e.g., arresting the development of the disease or condition, relieving the disease or condition, causing regression of the disease or condition, relieving a condition caused by the disease or condition, or stopping the symptoms of the disease or condition either prophylactically and/or therapeutically.

Anatomy of the Ear 100391 As shown in the illustration below, the outer ear is the external portion of the organ and is composed of the pinna (auricle), the auditory canal (external auditory meatus) and the outward facing portion of the tympanic membrane, also known as the ear drum. The pinna, which is the fleshy part of the external ear that is visible on the side of the head, collects sound waves and directs them toward the auditory canal. Thus, the function of the outer ear, in part, is to collect and direct sound waves towards the tympanic membrane and the middle ear.

100401 The middle ear is an air-filled cavity, called the tympanic cavity, behind the tympanic membrane. The tympanic membrane, also known as the ear drum, is a thin membrane that separates the external ear from the middle ear. The middle ear lies within the temporal bone, and includes within this space the three ear bones (auditory ossicles): the malleus, the incus and the stapes. The auditory ossicles are linked together via tiny ligaments, which form a bridge across the space of the tympanic cavity. The malleus, which is attached to the tympanic membrane at one end, is linked to the incus at its anterior end, which in turn is linked to the stapes. The stapes is attached to the oval window, one of two windows located within the tympanic cavity. A fibrous tissue layer, known as the annular ligament connects the stapes to the oval window. Sound waves from the outer ear first cause the tympanic membrane to vibrate. The vibration is transmitted across to the cochlea through the auditory ossicles and oval window, which transfers the motion to the fluids in the auris interna. Thus, the auditory ossicles are arranged to provide a mechanical linkage between the tympanic membrane and the oval window of the fluid-filled auris interna, where sound is transformed and transduced to the auris interna for further processing.

Stiffhess, rigidity or loss of movement of the auditory ossicles, tympanic membrane or oval window leads to hearing loss, e.g. otosclerosis, or rigidity of the stapes bone.

100411 The tympanic cavity also connects to the throat via the eustachian tube. The eustachian tube provides the ability to equalize the pressure between the outside air and the middle ear cavity. The round window, a component of the auris interna but which is also accessible within the tympanic cavity, opens into the cochlea of the auris interna. The round window is covered by round window membrane, which consists of three layers: an external or mucous layer, an intermediate or fibrous layer, and an internal membrane, which communicates directly with the cochlear fluid. The round window, therefore, has direct communication with the auris interna via the internal membrane.

100421 Movements in the oval and round window are interconnected, i.e. as the stapes bone transmits movement from the tympanic membrane to the oval window to move inward against the auris interna fluid, the round window (more correctly, round window membrane) is correspondingly pushed out and away from the cochlear fluid. This movement of the round window allows movement of fluid within the cochlea, which leads in turn to movement of the cochlear inner hair cells, allowing hearing signals to be transduced. Stiffness and rigidity in round window membrane leads to hearing loss because of the lack of ability of movement in the cochlear fluid.

Recent studies have focused on implanting mechanical transducers onto the round window, which bypasses the normal conductive pathway through the oval window and provides amplified input into the cochlear chamber.

100431 Auditory signal transduction takes place in the auris interna. The fluid-filled auris interna, or inner ear, consists of two major components: the cochlear and the vestibular apparatus. The auris intema is located in part within the osseous or bony labyrinth, an intricate series of passages in the temporal bone of the skull. The vestibular apparatus is the organ of balance and consists of the three semi-circular canals and the vestibule. The three semi-circular canals are arranged relative to each other such that movement of the head along the three orthogonal planes in space can be detected by the movement of the fluid and subsequent signal processing by the sensory organs of the semi-circular canals, called the crista ampullaris. The crista ampullaris contains hair cells and supporting cells, and is covered by a dome-shaped gelatinous mass called the cupula. The hairs of the hair cells are embedded in the cupula. The semi-circular canals detect dynamic equilibrium, the equilibrium of rotational or angular movements.

100441 When the head turns rapidly, the semicircular canals move with the head, but endolymph fluid located in the membranous semi-circular canals tends to remain stationary. The endolymph fluid pushes against the cupula, which tilts to one side. As the cupula tilts, it bends some of the hairs on the hair cells of the crista ampullaris, which triggers a sensory impulse. Because each semicircular canal is located in a different plane, the corresponding crista ampullaris of each semi-circular canal responds differently to the same movement of the head. This creates a mosaic of impulses that are transmitted to the central nervous system on the vestibular branch of the vestibulocochlear nerve. The central nervous system interprets this information and initiates the appropriate responses to maintain balance. Of importance in the central nervous system is the cerebellum, which mediates the sense of balance and equilibrium.

100451 The vestibule is the central portion of the auris interna and contains mechanoreceptors bearing hair cells that ascertain static equilibrium, or the position of the head relative to gravity. Static equilibrium plays a role when the head is motionless or moving in a straight line. The membranous labyrinth in the vestibule is divided into two sac-like structures, the utricle and the saccule. Each structure in turn contains a small structure called a macula, which is responsible for maintenance of static equilibrium. The macula consists of sensory hair cells, which are embedded in a gelatinous mass (similar to the cupula) that covers the macula. Grains of calcium carbonate, called otoliths, are embedded on the surface of the gelatinous layer.

100461 When the head is in an upright position, the hairs are straight along the macula. When the head tilts, the gelatinous mass and otoliths tilts correspondingly, bending some of the hairs on the hair cells of the macula. This bending action initiates a signal impulse to the central nervous system, which travels via the vestibular branch of the vestibulocochlear nerve, which in turn relays motor impulses to the appropriate muscles to maintain balance.

100471 The cochlea is the portion of the auris interna related to hearing. The cochlea is a tapered tube-like structure which is coiled into a shape resembling a snail. The inside of the cochlea is divided into three regions, which is further defined by the position of the Reissner' s membrane and the basilar membrane. The portion above the Reissner' s membrane is the scala vestibuli, which extends from the oval window to the apex of the cochlea and contains perilymph fluid, an aqueous liquid low in potassium and high in sodium content. The basilar membrane defines the scala tympani region, which extends from the apex of the cochlea to the round window and also contains perilymph. The basilar membrane widens from the base to the apex. The hair cells of the Organ of Corti, situated on the basilar membrane, vibrate when activated by sound. In between the scala vestibuli and the scala tympani is the cochlear duct (scala media), which ends as a closed sac at the apex of the cochlea. The cochlear duct contains endolymph fluid, which is similar to cerebrospinal fluid and is high in potassium.

100481 The organ of Corti, the sensory organ for hearing, is located on the basilar membrane and extends upward into the cochlear duct. The organ of Corti contains hair cells, which have hairlike projections that extend from their free surface, and contacts a gelatinous surface called the tectorial membrane. Although hair cells have no axons, they are surrounded by sensory nerve fibers that form the cochlear branch of the vestibulocochlear nerve (cranial nerve VIII).

100491 As discussed, the oval window, also known as the elliptical window communicates with the stapes to relay sound waves that vibrate from the tympanic membrane. Vibrations transferred to the oval window increases pressure inside the fluid-filled cochlea via the perilymph and scala vestibuli/scala tympani, which in turn causes the round window membrane to expand in response. The concerted inward pressing of the oval window/outward expansion of the round window allows for the movement of fluid within the cochlea without a change of intra-cochlear pressure. However, as vibrations travel through the perilymph in the scala vestibuli, they create corresponding oscillations in the Reissner's membrane. These corresponding oscillations travel through the endolymph of the cochlear duct, and transfer to the basilar membrane. When the basilar membrane oscillates, or moves up and down, the organ of Corti moves along with it. The hair cell receptors in the Organ of Corti with their own contractility to amplifj the response then move against the tectorial membrane, causing a mechanical deformation in the tectorial membrane. This mechanical deformation initiates the nerve impulse which travels via the cochlear nerve to the central nervous system, mechanically transmitting the sound wave received into signals that are subsequently processed by the central nervous system.

Diseases Excitotoxicity 100501 As used herein, "excitotoxicity" refers to the death of or damaging of a neuron and/or otic hair cell due to the presence of excess glutamate and/or similar neurotransmitters.

100511 Glutamate is the most abundant excitatory neurotransmitter in the central nervous system. In certain instances, pre-synaptic neurons release glutamate upon stimulation. In certain instances, glutamate flows across a synapse, binds to receptors located on post-synaptic neurons, and activates these neurons. Glutamate receptors include the NMDA, AMPA, and kainate receptors. Glutamate transporters are tasked with removing extracellular glutamate from the synapse. Certain events (e.g. ischemia or and stroke) damage glutamate transporters. In certain instances, damage to glutamate transporters results in excess glutamate accumulating in the synapse. In certain instances, excess glutamate in synapses results in the over-activation of the glutamate receptors.

100521 The AMPA receptor is activated by the binding of both glutamate and AMPA. In certain instances, activation of certain isoforms of the AMPA receptor results in the opening of ion channels located in the plasma membrane of the neuron. When the channels open, Na and Ca2 ions flow into the neuron and K ions flow out of the neuron.

100531 The NMDA receptor is activated by the binding of both glutamate and NMDA. In certain instances, activation of the NMDA receptor results in the opening of ion channels located in the plasma membrane of the neuron. However, these channels are blocked by Mg2 ions. Activation of the AMPA receptor results in the expulsion of Mg2+ ions from the ion channels into the synapse. When the ion channels open, and the Mg2 ions + 2+.

evacuate the ion channels, Na and Ca ions flow into the neuron, and K ions flow out of the neuron.

100541 In certain instances, excitotoxicity occurs when the NMDA receptor and AMPA receptors are over-activated by the binding of excessive amounts of ligands (e.g., abnormal amounts of glutamate). In certain instances, the over-activation of these receptors causes excessive opening of the ion channels under their control.

This allows abnormally high levels of Ca2 and Na to enter the neuron. The influx of these levels of Ca2 and Na into the neuron causes the neuron to fire more often than normal. This increased firing yields a rapid buildup of free radicals and inflammatory compounds. In certain instances, free radicals damage the mitochondria, depleting the cell's energy stores. Further, excess levels of Ca2 and Na ions activate excess levels of enzymes including, but not limited to, phospholipases, endonucleases, and proteases. The over-activation of these enzymes results in damage to the cytoskeleton, plasma membrane, mitochondria, and DNA of the neuron. In certain instances, such damage results in the activation of apoptotic genes. Additionally, the transcription of multiple pro-apoptotic genes and anti-apoptotic genes are controlled by Ca2 levels. In certain instances, excess Ca2 results in the upregulation of the pro-apoptotic genes and the down-regulation of anti-apoptotic genes.

Tinnitus 100551 As used herein, "tinnitus" refers to a disorder characterized by the perception of sound in the absence of any external stimuli. In certain instances, tinnitus occurs in one or both ears, continuously or sporadically, and is most often described as a ringing sound. It is most often used as a diagnostic symptom for other diseases. There are two types of tinnitus: objective and subjective. The former is a sound created in the body which is audible to anyone. The latter is audible only to the affected individual. Studies estimate that over 50 million Americans experience some form of tinnitus. Of those 50 million, about 12 million experience severe tinnitus.

100561 There are several treatments for tinnitus. Lidocaine, administered by IV, reduces or eliminates the noise associated with tinnitus in about 60-80% of sufferers. Selective neurotransmitter reuptake inhibitors, such as nortriptyline, sertraline, and paroxetine, have also demonstrated efficacy against tinnitus. Benzodiazepines are also prescribed to treat tinnitus.

Glutamate receptor antagonists 100571 Provided herein are methods of treating an otic disorder characterized by the dysregulation (e.g., over-activation or over-stimulation) of a glutamate receptor. In some embodiments, a method disclosed herein comprises administering to an individual in need thereof a composition comprising a glutamate receptor antagonist. Glutamate receptor antagonists which are not disclosed herein but which are useful for the amelioration or eradication of otic disorders are expressly included and intended within the scope of the embodiments presented.

100581 Contemplated for use with the formulations disclosed herein are agents that modulate the degeneration of neurons and/or hair cells of the auris, and agents for treating or ameliorating hearing loss or reduction resulting from destroyed, stunted, malfunctioning, damaged, fragile or missing hairs in the inner ear. Accordingly, some embodiments incorporate the use of agents which modulate glutamate receptors. In some embodiments, the glutamate receptor is the NMDA receptor.

100591 In some embodiments, the glutamate receptor antagonist is an NMDA receptor antagonist. In some embodiments, the glutamate receptor antagonist is a non-competitive antagonist. In some embodiments, the glutamate receptor antagonist is a small molecule. In some embodiments, the glutamate receptor antagonist is 1-aminoadamantane; dextromethorphan; dextrorphan; ibogaine; ifenprodil; (S)-ketamine; (R)-ketamine; memantine; dizocilpine (MK-801); gacyclidine; traxoprodil; D-2-amino-5-phosphonopentanoic acid (D-AP5); 3-((�)2-carboxypiperazin-4-yl)-propyl-1 -phosphonic acid (CPP); conantokin; 7-chlorokynurenate (7-CK); licostinel; nitrous oxide; phencyclidine; riluzole; tiletamine; aptiganel; remacimide; DCKA (5;7-dichlorokynurenic acid); kynurenic acid; 1 -aminocyclopropanecarboxylic acid (ACPC); AP7 (2-amino-7-phosphonoheptanoic acid); APV (R-2-amino-5-phosphonopentanoate); CPPene (3-[(R)-2-carboxypiperazin-4-yl]-prop-2-enyl-1 -phosphonic acid); (+)-(1 S; 2S)-i -(4-hydroxy-phenyl)-2-(4-hydroxy-4-phenylpiperidino)-1 -pro-panol; (is, 2S)-1 -(4-hydroxy-3- methoxyphenyl)-2-(4-hydroxy-4-phenylpiperi-dino)-1 -propanol; (3R, 4S)-3 -(4-(4-fluorophenyl)-4- hydroxypiperidin-1 -yl-)-chroman-4,7-diol; (1R*; 2R*) 1 -(4-hydroxy-3-methylphenyl)-2-(4-(4-fluoro-phenyl)-4-hydroxypiperidin-1 -yl)-propan-1 -ol-mesylate; or combinations thereof. In some embodiments, the NMDA receptor antagonist is an arylcycloalkylamine. In some embodiments, the NMDA receptor antagonist is (S)-ketamine or a salt thereof. In some embodiments, the NMDA receptor antagonist is a chinazoline. In some embodiments, the NMDA receptor antagonist is 7-CK or a salt thereof.

100601 In some embodiments, the glutamate receptor antagonist is an NMDA receptor antagonist. In some embodiments, the glutamate receptor antagonist is a peptide. In some embodiments, the glutamate receptor antagonist is a fusion peptide comprising (a) a transporter peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins. As used herein, a "transporter peptide" means a peptide that promotes peptide penetration into cells and tissues. In some embodiments, a transporter peptide is TAT.

100611 In some embodiments, the glutamate receptor antagonist is a fusion peptide comprising (a) a TAT peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins.

In some embodiments, the glutamate receptor antagonist is a fusion peptide comprising (a) a (D)-TAT peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins. In some embodiments, the glutamate receptor antagonist is a fusion peptide comprising (a) a transporter peptide, and (b) an NR2B9c peptide. In some embodiments, the glutamate receptor antagonist is a fusion peptide comprising (a) a transporter peptide, and (b) a (D)-NR2B9c peptide. In some embodiments, the glutamate receptor antagonist is a fusion peptide comprising (a) a (D)-TAT peptide, and (b) a (D)-NR2B9c peptide. In some embodiments, the glutamate receptor antagonist is a fusion peptide comprising (a) a transporter peptide, and (b) a (L)-NR2B9c peptide.

100621 In certain instances, the over-activation of the NMDA glutamate receptors by the binding of excessive amounts of glutamate, results in the excessive opening of the ion channels under its control. In certain instances, this results in abnormally high levels of Ca2 and Na entering the neuron. In certain instances, the influx of Ca2 and Na into the neuron activates multiple enzymes including, but not limited to, phospholipases, endonucleases, and proteases. In certain instances, the over-activation of these enzymes results in damage to the cytoskeleton, plasma membrane, mitochondria, and DNA of the neuron. Further, in certain instances, the transcription of multiple pro-apoptotic genes and anti-apoptotic genes are controlled by Ca2 levels.

General Methods of Sterilization 100631 Provided herein are methods of treating an otic disorder characterized by the dysregulation (e.g., over-activation or over-stimulation) of a glutamate receptor. In some embodiments, a method disclosed herein comprises administering to an individual in need thereof a composition comprising a glutamate receptor antagonist or agonist. Included within the embodiments disclosed herein are means and processes for sterilization of a pharmaceutical composition disclosed herein for use in humans. The goal is to provide a safe pharmaceutical product, relatively free of infection causing micro-organisms. The U. S. Food and Drug Administration has provided regulatory guidance in the publication Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing available at: http://www.fda.gov/cder'guidance/5882fn1.htm, which is incorporated herein by reference in its entirety.

100641 The environment of the inner ear is an isolated environment. The endolymph and the perilymph are static fluids and are not in direct contact with the circulatory system. As a result, the response of the immune system within the microenvironment of the inner ear is limited compared to the disease fighting machinery that is accessible to other parts of the body. The inner ear is therefore susceptible to long-term infections. Further, the cochlear potential is highly sensitive to changes in pH and osmolality in the endolymph and the perilymph. In certain instances, microbial infections and any resulting immune response disrupt the pH and osmolality of the endolymph and the perilymph, negatively impact hearing. Due to the susceptibilty of the inner ear to infections and the negative results of such infections, auris formulations require a level of sterility that has not been

recognized hitherto in this field.

100651 As used herein, sterilization means a process used to destroy or remove microorganisms that may be present in a product or packaging. Any suitable method available for sterilization of objects and compositions is used. Available methods for the inactivation of microorganisms include, but are not limited to, the application of extreme heat, lethal chemicals, or gamma radiation. In one embodiment is a process for the preparation of an otic therapeutic formulation comprising subjecting the formulation to a sterilization method selected from heat sterilization, chemical sterilization, radiation sterilization or filtration sterilization. The method used depends largely upon the nature of the device or composition to be sterilized. Detailed descriptions of many methods of sterilization are given in Chapter 40 of Remington: The Science and Practice of Pharmacy, published by Lippincott, Williams & Wilkins, and is incorporated by reference with respect to this subject matter.

Sterilization by Heat 100661 Many methods are available for sterilization by the application of extreme heat. One method is through the use of a saturated steam autoclave. In this method, saturated steam at a temperature of at least 121 °C is allowed to contact the object to be sterilized. The transfer of heat is either directly to the microorganism, in the case of an object to be sterilized, or indirectly to the microorganism by heating the bulk of an aqueous solution to be sterilized. This method is widely practiced as it allows flexibility, safety and economy in the sterilization process.

100671 Dry heat sterilization is a method which is used to kill microorganisms and perform depyrogenation at elevated temperatures. This process take place in an apparatus suitable for heating HEPA-filtered microorganism-free air to temperatures of at least 160-180 °C for the sterilization process and to temperatures of at least 230-250 °C for the depyrogenation process. Water to reconstitute concentrated or powdered formulations is also sterilized by autoclave.

Chemical Sterilization 100681 Chemical sterilization methods are an alternative for products that do not withstand the extremes of heat sterilization. In this method, a variety of gases and vapors with germicidal properties, such as ethylene oxide, chlorine dioxide, formaldehyde or ozone are used. The germicidal activity of ethylene oxide, for example, arises from its ability to serve as a reactive alkylating agent. Thus, the sterilization process requires the ethylene oxide vapors to make direct contact with the product to be sterilized.

Radiation Sterilization 100691 One advantage of radiation sterilization is the ability to sterilize many types of products without heat degradation or other damage. The radiation commonly employed is beta radiation or alternatively, gamma radiation from a 60Co source. The penetrating ability of gamma radiation allows its use in the sterilization of many product types, including solutions, compositions and heterogeneous mixtures. The germicidal effects of irradiation arise from the interaction of gamma radiation with biological macromolecules. This interaction generates charged species and free radicals. Subsequent chemical reactions, such as rearrangements and cross-linking processes, result in the loss of normal function for these biological macromolecules. The formulations described herein are also optionally sterilized using beta irradiation.

Filtration 100701 Filtration sterilization is a method used to remove but not destroy microorganisms from solutions.

Membrane filters are used to filter heat-sensitive solutions. Such filters are thin, strong, homogenous polymers of mixed cellulosic esters (MCE), polyvinylidene fluoride (PVF; also known as PVDF), or polytetrafluoroethylene (PTFE) and have pore sizes ranging from 0.1 to 0.22 tim. Solutions of various characteristics are optionally filtered using different filter membranes. For example, PVF and PTFE membranes are well suited to filtering organic solvents while aqueous solutions are filtered through PVF or MCE membranes. Filter apparatus are available for use on many scales ranging from the single point-of-use disposable filter attached to a syringe up to commercial scale filters for use in manufacturing plants. The membrane filters are sterilized by autoclave or chemical sterilization. Validation of membrane filtration systems is performed following standardized protocols (Microbiological Evaluation of Filters for Sterilizing Liquids, Vol 4, No. 3. Washington, D.C: Health Industry Manufacturers Association, 1981) and involve challenging the membrane filter with a known quantity (ca. 1 0) of unusually small microorganisms, such as Brevundimonas diminuta (ATCC 19146).

100711 Pharmaceutical compositions are optionally sterilized by passing through membrane filters. Formulations comprising nanoparticles (U.S. Pat No. 6,139,870) or multilamellar vesicles (Richard et al., International Journal of Pharmaceutics (2006), 312(1-2): 144-50) are amenable to sterilization by filtration through 0.22 tm filters without destroying their organized structure.

100721 In some embodiments, the methods disclosed herein comprise sterilizing the formulation (or components thereof) by means of filtration sterilization. In another embodiment the auris-acceptable otic therapeutic agent formulation comprises a particle wherein the particle formulation is suitable for filtration sterilization. In a further embodiment said particle formulation comprises particles of less than 300 nm in size, of less than 200 nm in size, of less than 100 nm in size. In another embodiment the auris-acceptable formulation comprises a particle formulation wherein the sterility of the particle is ensured by sterile filtration of the precursor component solutions. In another embodiment the auris-acceptable formulation comprises a particle formulation wherein the sterility of the particle formulation is ensured by low temperature sterile filtration. In a further embodiment, said low temperature sterile filtration occurs at a temperature between 0 and 30 °C, or between 0 and 20 °C, or between 0 and 10 °C, or between 10 and 20 °C, or between 20 and 30 °C. In another embodiment is a process for the preparation of an auris-acceptable particle formulation comprising: filtering the aqueous solution containing the particle formulation at low temperature through a sterilization filter; lyophilizing the sterile solution; and reconstituting the particle formulation with sterile water prior to administration.

100731 In another embodiment the auris-acceptable otic therapeutic agent formulation comprises a nanoparticle formulation wherein the nanoparticle formulation is suitable for filtration sterilization. In a further embodiment the nanoparticle formulation comprises nanoparticles of less than 300 nm in size, of less than 200 nm in size, or of less than 100 nm in size. In another embodiment the auris-acceptable formulation comprises a microsphere formulation wherein the sterility of the microsphere is ensured by sterile filtration of the precursor organic solution and aqueous solutions. In another embodiment the auris-acceptable formulation comprises a thermoreversible gel formulation wherein the sterility of the gel formulation is ensured by low temperature sterile filtration. In a further embodiment, the low temperature sterile filtration occurs at a temperature between 0 and 30 °C, or between 0 and 20 °C, or between 0 and 10 °C, or between 10 and 20 °C, or between 20 and 30 °C. In another embodiment is a process for the preparation of an auris-acceptable thermoreversible gel formulation comprising: filtering the aqueous solution containing the thermoreversible gel components at low temperature through a sterilization filter; lyophilizing the sterile solution; and reconstituting the thermoreversible gel formulation with sterile water prior to administration.

Microorganisms 100741 Provided herein are methods of treating an otic disorder characterized by the dysregulation (e.g., over-activation or over-stimulation) of a glutamate receptor. In some embodiments, a method disclosed herein comprises administering to an individual in need thereof a composition comprising a glutamate receptor antagonist or agonist. Acceptable sterility levels are based on applicable standards that define therapeutically acceptable otic compositions, including but not limited to United States Pharmacopeia Chapters <1111> et seq.

For example, acceptable sterility levels include 10 colony forming units (cfu) per gram of formulation, 50 cfu per gram of formulation, 100 cfu per gram of formulation, 500 cfu per gram of formulation or 1000 cfu per gram of formulation. In addition, acceptable sterility levels include the exclusion of specified objectionable microbiological agents. By way of example, specified objectionable microbiological agents include but are not limited to Escherichia coli (E. coli), Salmonella sp., Pseudomonas aeruginosa (P. aeruginosa) and/or other specific microbial agents.

100751 Sterility of the auris-acceptable otic therapeutic agent formulation is confirmed through a sterility assurance program in accordance with United States Pharmacopeia Chapters <61>, <62> and <71>. A key component of the sterility assurance quality control, quality assurance and validation process is the method of sterility testing. Sterility testing, by way of example only, is performed by two methods. The first is direct inoculation wherein a sample of the composition to be tested is added to growth medium and incubated for a period of time up to 21 days. Turbidity of the growth medium indicates contamination. Drawbacks to this method include the small sampling size of bulk materials which reduces sensitivity, and detection of microorganism growth based on a visual observation. An alternative method is membrane filtration sterility testing. In this method, a volume of product is passed through a small membrane filter paper. The filter paper is then placed into media to promote the growth of microorganisms. This method has the advantage of greater sensitivity as the entire bulk product is sampled. The commercially available Millipore Steritest sterility testing system is optionally used for determinations by membrane filtration sterility testing. For the filtration testing of creams or ointments Steritest filter system No. TLHVSL2 10 may be used. For the filtration testing of emulsions or viscous products Steritest filter system No. TLAREM2 10 or TDAREM2 10 may be used. For the filtration testing of pre-filled syringes Steritest filter system No. TTHASY2 10 may be used. For the filtration testing of material dispensed as an aerosol or foam Steritest filter system No. TTHVA2 10 may be used. For the filtration testing of soluble powders in ampoules or vials Steritest filter system No. TTHADA21O or TTHADV21 0 may be used.

100761 Testing for E. coli and Salmonella includes the use of lactose broths incubated at 30-35 °C for 24-72 hours, incubation in MacConkey and/or EMB agars for 1 8-24 hours, and/or the use of Rappaport medium. Testing for the detection of P. aeruginosa includes the use of NAC agar. United States Pharmacopeia Chapter <62> further enumerates testing procedures for specified objectionable microorganisms.

Endotoxins 100771 Provided herein are methods of treating an otic disorder characterized by the dysregulation (e.g., over-activation or over-stimulation) of a glutamate receptor. In some embodiments, a method disclosed herein comprises administering to an individual in need thereof a composition comprising a glutamate receptor antagonist or agonist. An additional aspect of the sterilization process is the removal of by-products from the killing of microorganisms (hereinafter, "Product"). The process of depyrogenation removes pyrogens from the sample. Pyrogens are endotoxins or exotoxins which induce an immune response. An example of an endotoxin is the lip opolysaccharidc (LPS) molecule found in the cell wall of gram-negative bacteria. While sterilization procedures such as autoclaving or treatment with ethylene oxide kill the bacteria, the LPS residue induces a proinflammatoiy immune response, such as septic shock. Because the molecular size of endotoxins can vary widely, the presence of endotoxins is expressed in "endotoxin units" (EU). One EU is equivalent to 100 picograms of E. coli LPS. Humans can develop a response to as little as 5 EU/kg of body weight. In some embodiments, the auris-acceptable otic therapeutic agent formulation has less than 5 EU/kg Product. In other embodiments, the auris-acceptable otic therapeutic agent formulation has less than 1 EU/kg of Product. In additional embodiments, the auris-acceptable otic therapeutic agent formulation has less than 0.2 EU/kg of Product. Pyrogen detection, by way of example only, is performed by several methods. The rabbit pyrogen test and the Limulus amebocyte lysate test are both specified in the United States Pharmacopeia Chapters <85> and <151> (U5P23/NF 18, Biological Tests, The United States Pharmacopeial Convention, Rockville, MD, 1995).

Alternative pyrogen assays have been developed based upon the monocyte activation-cytokine assay. Uniform cell lines suitable for quality control applications have been developed and have demonstrated the ability to detect pyrogenicity in samples that have passed the rabbit pyrogen test and the Limulus amebocyte lysate test (Taktak et al, J. Pharm. Pharmacol. (1990), 43:578-82). In an additional embodiment, the auris-acceptable otic therapeutic agent formulation is subject to depyrogenation. In a further embodiment, the process for the manufacture of the auris-acceptable otic therapeutic agent formulation comprises testing the formulation for pyrogenicity.

pH and Practical Osmolarity 100781 As used herein, "practical osmolarity" means the osmolarity of the materials that cross (or penetrate) the round window membrane. Practical osmolarity does not include the osmolarity of materials that do not cross (or penetrate) the round window membrane (e.g., polyoxyethylene-polyoxypropylene copolymers).

100791 Provided herein are methods of treating an otic disorder characterized by the dysregulation (e.g., over-activation or over-stimulation) of a glutamate receptor. In some embodiments, a method disclosed herein comprises administering to an individual in need thereof a composition comprising a glutamate receptor antagonist and a pH adjusting agent to provide an endolymph or perilymph suitable pH. In some embodiments, a method disclosed herein comprises administering to an individual in need thereof a composition comprising a glutamate receptor antagonist and a buffering agent to provide an endolymph or perilymph suitable practical osmolarity. In some embodiments, a method disclosed herein comprises administering to an individual in need thereof a composition comprising a glutamate receptor antagonist, a pH adjusting agent, and a buffering agent to provide an endolymph or perilymph suitable pH and practical osmolarity.

100801 The main cation present in the endolymph is potassium. In addition the endolymph has a high concentration of positively charged amino acids. The main cation present in the perilymph is sodium. In certain instances, the ionic composition of the endolymph and perilymph regulate the electrochemical impulses of hair cells. In certain instances, any change in the ionic balance of the endolymph or perilymph results in a loss of hearing due to changes in the conduction of electrochemical impulses along otic hair cells. In some embodiments, a composition disclosed herein does not disrupt the ionic balance of the perilymph. In some embodiments, a composition disclosed herein has an ionic balance that is the same as or substantially the same as the perilymph.

In some embodiments, a composition disclosed herein does not disrupt the ionic balance of the endolymph. In some embodiments, a composition disclosed herein has an ionic balance that is the same as or substantially the same as the endolymph.

100811 The endolymph and the perilymph have a pH that is close to the physiological pH of blood. The endolymph has a pH range of about 7.2-7.9; the perilymph has a pH range of about 7.2-7.4. The in situ pH of the proximal endolymph is about 7.4 while the pH of distal endolymph is about 7.9.

100821 In some embodiments, the pH of a composition described herein is adjusted (e.g., by use of a buffer) to an endolymph-compatible pH range of about 7.0 to 8.0, and a preferred pH range of about 7.2 -7.9. In some embodiments, the pH of the auris formulations described herein is adjusted (e.g., by use of a buffer) to a perilymph -compatible pH of about 7.0 -7.6, and a preferred pH range of about 7.2-7.4.

100831 In general, the endolymph has a higher osmolality than the perilymph. For example, the endolymph has an osmolality of about 304 mOsm!kg H20 while the perilymph has an osmolality of about 294 mOsmlkg H20. In some embodiments, compositions described herein are formulated to provide a practical osmolarity of about 250 to about 320 mM (osmolality of about 250 to about 320 mOsmlkg H20) ; and preferably about 270 to about 320 mM (osmolality of about 270 to about 320 mOsm!kg H20). In specific embodiments, the practical osmolarity/osmolality of the present formulations is adjusted, for example, by the use of appropriate salt concentrations (e.g., concentration of potassium salts) or the use of tonicity agents which renders the formulations endolymph-compatible and/or perilymph-compatible (i.e. isotonic with the endolymph and/or perilymph. In some instances, the endolymph-compatible and/or perilymph-compatible formulations described herein cause minimal disturbance to the environment of the inner ear and cause minimum discomfort (e.g, dizzines) to a mammal upon adminstration.

100841 Suitable pH adjusting agents or buffers include, but are not limited to acetate, bicarbonate, ammonium chloride, citrate, phosphate, pharmaceutically acceptable salts thereof and combinations or mixtures thereof.

100851 In one embodiment, when one or more buffers are utilized in the formulations of the present disclosure, they are combined, e.g., with a pharmaceutically acceptable vehicle and are present in the final formulation, e.g., in an amount ranging from about 0.1% to about 20%, from about 0.5% to about 10%. In certain embodiments of the present disclosure, the amount of buffer included in the gel formulations are an amount such that the pH of the gel formulation does not interfere with the auris media or auris interna's natural buffering system, or does not interfere with the natural pH of the endolymph or perilymph: depending on where in the cochlea a composition disclosed herein is targeted. In some embodiments, from about 5 mM to about 200 mM concentration of a buffer is present in the gel formulation. In certain embodiments, from about a 20 mM to about a 100 mM concentration of a buffer is present.

100861 In one embodiment is a buffer such as acetate or citrate at slightly acidic pH. In one embodiment the buffer is a sodium acetate buffer having a pH of about 4.5 to about 6.5. In one embodiment the buffer is a sodium citrate buffer having a pH of about 5.0 to about 8.0, or about 5.5 to about 7.0.

100871 In an alternative embodiment, the buffer used is tris(hydroxymethyl)aminomethane, bicarbonate, carbonate or phosphate at slightly basic pH. In one embodiment, the buffer is a sodium bicarbonate buffer having a pH of about 6.5 to about 8.5, or about 7.0 to about 8.0. In another embodiment the buffer is a sodium phosphate dibasic buffer having a pH of about 6.0 to about 9.0.

100881 In some embodiments, the pharmaceutical formulations described herein are stable with respect to pH over a period of any of at least about 1 day, at least about 2 days, at least about 3 days, at least about 4 days, at least about 5 days, at least about 6 days, at least about 1 week, at least about 2 weeks, at least about 4 weeks, at least about 6 weeks, at least about 8 weeks, at least about 4 months, at least about S months, or at least about 6 months. In other embodiments, the formulations described herein are stable with respect to pH over a period of at least about 1 week to about 1 month. Also described herein are formulations that are stable with respect to pH over a period of at least about 1 month.

Particle size 100891 Size reduction is used to increase surface area and/or modulate formulation dissolution properties. It is also used to maintain a consistent average particle size distribution (PSD) (e.g., micrometer-sized particles, nanometer-sized particles or the like) for any composition described herein. In some instances, any composition described herein comprises mulitparticulates, i.e., a plurality of particle sizes (e.g., micronized particles, nano-sized particles, non-sized particles); i.e, the formulation is a multiparticulate formulation. In some embodiments, any composition described herein comprises one or more multiparticulate (e.g., micronized) NMDA receptor antagonists. Micronization is a process of reducing the average diameter of particles of a solid material.

Micronized particles are from about micrometer-sized in diameter to about picometer -sized in diameter. In some embodiments, the use of multiparticulates (e.g., micronized particles) of an NMDA receptor antagonist allows for extended and/or sustained release of the NMDA receptor antagonist from any composition described herein compared to a composition comprising non-multiparticulate (e.g, non-micronized) NMDA receptor antagonists.

In some instances, compositions comprising multiparticulate (e.g. micronized) NMDA receptor antagonists are ejected from a lmL syringe adapted with a 27G needle without any plugging or clogging.

100901 In some instances, any particle in any composition described herein is a coated particle (e.g., a coated micronized particle) and/or a microsphere and/or a liposomal particle. Particle size reduction techniques include, by way of example, grinding, milling (e.g., air-attrition milling (jet milling), ball milling), coacervation, high pressure homogenization, spray drying and/or supercritical fluid crystallization. In some instances, particles are sized by mechanical impact (e.g., by hammer mills, ball mill and/or pin mills). In some instances, particles are sized via fluid energy (e.g., by spiral jet mills, loop jet mills, and/or fluidized bed jet mills). In some embodiments compositions described herein comprise crystalline particles. In some embodiments, compositions described herein comprise amorphous particles. In some embodiments, compositions described herein comprise NMDA receptor antagonist particles wherein the NMDA receptor antagonist is a free base, or a salt, or a prodrug, or any combination thereof.

100911 In some instances, a combination of an NMDA receptor antagonist and a salt of the NMDA receptor antagonist is used to prepare pulsed release NMDA receptor antagonist compositions using the procedures described herein. In some compositions, a combination of a micronized NMDA receptor antagonist (and/or salt or prodrug thereof) and coated particles (e.g., nanoparticles, liposomes, microspheres) is used to prepare pulsed release NMDA receptor antagonist compositions using any procedure described herein. Alterntaively, a pulsed release profile is achieved by solubilizing up to 20% of the delivered dose of the NMDA receptor antagonist (e.g., micronized NMDA receptor antagonist, or free base or salt or prodrug thereof; multiparticulate NMDA receptor antagonist, or free base or salt or prodrug thereof) with the aid of cyclodextrins, surfactants (e.g., poloxamers (407, 338, 188), tween (80, 60, 20,8 1), PEG-hydrogenated castor oil, cosolvents like N-methyl-2-Pyrrolidone or the like and preparing pulsed release compositions using any procedure described herein.

100921 In some specific embodiments, any NMDA receptor antagonist composition described herein comprises one or more micronized NMDA receptor antagonists. In some of such embodiments, a micronized NMDA receptor antagonist comprises micronized particles, coated (e.g., with an extended release coat) micronized particles, or a combination thereof. In some of such embodiments, a micronized NMDA receptor antagonist comprising micronized particles, coated micronized particles, or a combination thereof, comprises an NMDA receptor antagonist as a free base, a salt, a prodrug or any combination thereof.

Pharmaceutical Compositions 100931 Provided herein are NMDA receptor antagonist compositions that ameliorate or lessen otic disorders characterized by loss of a plurality of cells (e.g., hair cell, or neurons). Further provided herein are methods comprising the administration of said NMDA receptor antagonist compositions. In some embodiments, the compositions comprise at least one of a carrier, an adjuvant (e.g., preserving, stabilizing, wetting or emulsifying agents), a solution promoter, a salt for regulating the osmotic pressure, and a buffer. In preferred embodiments, a composition described herein is preservative-free or substantially free of preservatives. In certain instances, such a composition provides a safer, less-ototoxic composition.

100941 Such carriers, adjuvants, and other excipients will be compatible with the environment in the targeted auris structure(s). Accordingly, specifically contemplated are carriers, adjuvants and excipients that lack ototoxicity or are minimally ototoxic in order to allow effective treatment of the otic disorders contemplated herein with minimal side effects in the targeted regions or areas. To prevent ototoxicity, a composition disclosed herein is optionally targeted to distinct regions of the targeted auris structures, including but not limited to the tympanic cavity, vestibular bony and membranous labyrinths, cochlear bony and membranous labyrinths and other anatomical or physiological structures located within the auris interna. In some embodiments, a composition disclosed herein includes otoprotective agents, such as antioxidants, alpha lipoic acid, calicum, fosfomycin or iron chelators.

Mucoadhesives 100951 In other embodiments, a composition disclosed herein further comprises a mucoadhesive excipient to allow adhesion to the external mucous layer of the round window membrane. The term mucoadhesion' is used for materials that bind to the mucin layer of a biological membrane, such as the external membrane of the 3-layered round window membrane. To serve as round window membrane mucoadhesive polymers, the polymers possess some general physiochemical features such as predominantly anionic hydrophilicity with numerous hydrogen bond forming groups, suitable surface property for wetting mucus/mucosal tissue surfaces or sufficient flexibility to penetrate the mucus network.

100961 Round window membrane mucoadhesive agents that are used with the auris-acceptable formulations include, but are not limited to, at least one soluble polyvinylpyrrolidone polymer (PVP); a water-swellable, but water-insoluble, fibrous, cross-linked carboxy-functional polymer; a crosslinked poly(acrylic acid) (e.g. Carbopol� 947P); a carbomer homopolymer; a carbomer copolymer; a hydrophilic polysaccharide gum, maltodextrin, a cross-linked alignate gum gel, a water-dispersible polycarboxylated vinyl polymer, at least two particulate components selected from the group consisting of titanium dioxide, silicon dioxide, and clay, or a mixture thereof. The round window membrane mucoadhesive agent is optionally used in combination with an auris-acceptable viscosity increasing excipient, or used alone to increase the interaction of the composition with the mucosal layer target otic component. In one non-limiting example, the mucoadhesive agent is maltodextrin and/or an alginate gum. When used, the round window membrane mucoadhesive character imparted to the composition is at a level that is sufficient to deliver an effective amount of the corticosteroid composition to, for example, the mucosal layer of round window membrane or the crista fenestrae cochleae in an amount that coats the mucosal membrane, and thereafter deliver the composition to the affected areas, including by way of example only, the vestibular and/or cochlear structures of the auris interna. One method for determining sufficient mucoadhesiveness includes monitoring changes in the interaction of the composition with a mucosal layer, including but not limited to measuring changes in residence or retention time of the composition in the absence and presence of the mucoadhesive excipient.

100971 In one non-limiting example, the round window membrane mucoadhesive agent is maltodextrin.

Maltodextrin is a carbohydrate produced by the hydrolysis of starch that is optionally derived from corn, potato, wheat or other plant products. Maltodextrin is optionally used either alone or in combination with other round window membrane mucoadhesive agents to impart mucoadhesive characteristics on the compositions disclosed herein. In some embodiments, a combination of maltodextrin and a carbopol polymer are used to increase the round window membrane mucoadhesive characteristics of the compositions disclosed herein.

100981 In another embodiment, the round window membrane mucoadhesive agent is an allyl-glycoside and/or a saccharide alkyl ester. As used herein, an "alkyl-glycoside" means a compound comprising any hydrophilic saccharide (e.g. sucrose, maltose, or glucose) linked to a hydrophobic alkyl. In some embodiments, the round window membrane mucoadhesive agent is an alkyl-glycoside wherein the alkyl-glycoside comprises a sugar linked to a hydrophobic alkyl (e.g., an alkyl comprising about 6 to about 25 carbon atoms) by an amide linkage, an amine linkage, a carbamate linkage, an ether linkage, a thioether linkage, an ester linkage, a thioester linkage, a glycosidic linkage, a thioglycosidic linkage, and/or a ureide linkage. In some embodiments, the round window membrane mucoadhesive agent is a hexyl-, heptyl-, octyl-, nonyl-, decyl-, undecyl-, dodecyl-, tridecyl-, tetradecyl, pentadecyl-, hexadecyl-, heptadecyl-, and octadecyl a-or 13-D-maltoside; hexyl-, heptyl-, octyl-, nonyl- decyl-, undecyl-, dodecyl-, tridecyl-, tetradecyl, pentadecyl-, hexadecyl-, heptadecyl-, and octadecyl a-or J3-D- glucoside; hexyl-, heptyl-, octyl-, nonyl-, decyl-, undecyl-, dodecyl-, tridecyl-, tetradecyl, pentadecyl-, hexadecyl- heptadecyl-, and octadecyl a-or J3-D-sucroside; hexyl-, heptyl-, octyl-, dodecyl-, tridecyl-, and tetradecyl-J3-D-thiomaltoside; heptyl-or octyl-1-thio-a-or 13-D-glucopyranoside; alkylthiosucroses; alkyl maltotriosides; long chain aliphatic carbonic acid amides of sucrose 13-amino-alkyl ethers; derivatives of palatinose or isomaltamine linked by an amide linkage to an alkyl chain and derivatives of isomaltamine linked by urea to an alkyl chain; long chain aliphatic carbonic acid ureides of sucrose 13-amino-alkyl ethers and long chain aliphatic carbonic acid amides of sucrose 13-amino-alkyl ethers. In some embodiments, the round window membrane mucoadhesive agent is an alkyl-glycoside wherein the alkyl glycoside is maltose, sucrose, glucose, or a combination thereof linked by a glycosidic linkage to an alkyl chain of 9-16 carbon atoms (e.g., nonyl-, decyl-, dodecyl-and tetradecyl sucroside; nonyl-, decyl-, dodecyl-and tetradecyl glucoside; and nonyl-, decyl-, dodecyl-and tetradecyl maltoside). In some embodiments, the round window membrane mucoadhesive agent is an alkyl-glycoside wherein the alkyl glycoside is dodecylmaltoside, tridecylmaltoside, and tetradecylmaltoside. In some embodiments, the auris acceptable penetration enhancer is a surfactant comprising an alkyl-glycoside wherein the alkyl glycoside is tetradecyl-13-D-maltodise. In some embodiments, the round window membrane mucoadhesive agent is an alkyl-glycoside wherein the alkyl-glycoside is a disaccharide with at least one glucose. In some embodiments, the auris acceptable penetration enhancer is a surfactant comprising cz-D-glucopyranosyl-J3- glycopyranoside, n-Dodecyl-4-O-cz-D-glucopyranosyl-J3-glycopyranoside, and/or n-tetradecyl-4-O-cz-D-glucopyranosyl-J3-glycopyranoside. In some embodiments, the round window membrane mucoadhesive agent is an alkyl-glycoside wherein the alkyl-glycoside has a critical miscelle concentration (CMC) of less than about 1mM in pure water or in aqueous solutions. In some embodiments, the round window membrane mucoadhesive agent is an alkyl-glycoside wherein an oxygen atom within the alkyl-glycoside is substituted with a sulfur atom.

In some embodiments, the round window membrane mucoadhesive agent is an alkyl-glycoside wherein the alkylglycoside is the 13 anomer. In some embodiments, the round window membrane mucoadhesive agent is an alkyl-glycoside wherein the alkylglycoside comprises 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.5%, or 99.9% of the f3 anomer.

100991 In other embodiments, a composition disclosed herein further comprises a penetration enhancer excipient.

In another embodiment, the formulation further comprises one or more round window membrane penetration enhancers. Penetration across the round window membrane is enhanced by the presence of round window membrane penetration enhancers. Round window membrane penetration enhancers are chemical entities that facilitate transport of coadministered substances across the round window membrane. Round window membrane penetration enhancers are grouped according to chemical structure. Surfactants, both ionic and non-ionic, such as sodium lauryl sulfate, sodium laurate, polyoxyethylene-20-cetyl ether, laureth-9, sodium dodecylsulfate, dioctyl sodium sulfosuccinate, polyoxyethylene-9-lauryl ether (PLE), Tween� 80, nonylphenoxypolyethylene (NP-POE), polysorbates and the like, function as round window membrane penetration enhancers. Bile salts (such as sodium glycocholate, sodium deoxycholate, sodium taurocholate, sodium taurodihydrofusidate, sodium glycodihydrofusidate and the like), fatty acids and derivatives (such as oleic acid, caprylic acid, mono-and di-glycerides, lauric acids, acylcholines, caprylic acids, acylcarnitines, sodium caprates and the like), chelating agents (such as EDTA, citric acid, salicylates and the like), sulfoxides (such as dimethyl sulfoxide (DMSO), decylmethyl sulfoxide and the like), and alcohols (such as ethanol, isopropanol, glycerol, propanediol and the like) also function as round window membrane penetration enhancers.

1001001 In some embodiments, a composition disclosed herein further comprises a viscosity enhancing agent. In some embodiments, a composition disclosed herein has a viscosity from about 100 to about 100,000 cP. In some embodiments, a composition disclosed herein has a viscosity from about 100 to about 50,000 cP, about 100 cP to about 1,000 cP, about 500 cP to about 1500 cP, about 1000 cP to about 3000 cP, about 2000 cP to about 8,000 cP, about 4,000 cP to about 50,000 cP, about 10,000 cP to about 500,000 cP, about 15,000 cP to about 1,000,000 cP.

1001011 Suitable viscosity-enhancing agents include by way of example only, hydroxypropyl methylcellulose, hydroxyethyl cellulose, polyvinylpyrrolidone, carboxymethyl cellulose, polyvinyl alcohol, sodium chondroitin sulfate, sodium hyaluronate. Other viscosity enhancing agents compatible with the targeted auris structure include, but are not limited to, acacia (gum arabic), agar, aluminum magnesium silicate, sodium alginate, sodium stearate, bladderwrack, bentonite, carbomer, carrageenan, Carbopol, xanthan, cellulose, microcrystalline cellulose (MCC), ceratonia, chitin, carboxymethylated chitosan, chondrus, dextrose, furcellaran, gelatin, Ghatti gum, guar gum, hectorite, lactose, sucrose, maltodextnn, mannitol, sorbitol, honey, maize starch, wheat starch, rice starch, potato starch, gelatin, sterculia gum, xanthum gum, gum tragacanth, ethyl cellulose, ethylhydroxyethyl cellulose, ethylmethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxyethylmethyl cellulose, hydroxypropyl cellulose, poly(hydroxyethyl methacrylate), oxypolygelatin, pectin, polygeline, povidone, propylene carbonate, methyl vinyl ether/maleic anhydride copolymer (PVM/MA), poly(methoxyethyl methacrylate), poly(methoxyethoxyethyl methacrylate), hydroxypropyl cellulose, hydroxypropylmethyl-cellulose (HPMC), sodium carboxymethyl-cellulose (CMC), silicon dioxide, polyvinylpyrrolidone (PVP: povidone), Splenda� (dextrose, maltodextrin and sucralose) or combinations thereof. In specific embodiments, the viscosity-enhancing excipient is a combination of MCC and CMC. In another embodiment, the viscosity-enhancing agent is a combination of carboxymethylated chitosan, or chitin, and alginate. The combination of chitin and alginate with the corticosteroids disclosed herein acts as a controlled release formulation, restricting the diffusion of the corticosteroids from the formulation. Moreover, the combination of carboxymethylated chitosan and alginate is optionally used to assist in increasing the permeability of the corticosteroids through the round window membrane.

Suspending Agents 1001021 In some embodiments, a formulation disclosed herein comprises a suspending agent. Suspending agents include by way example only, compounds such as polyvinylpyrrolidone, e.g., polyvinylpynolidone K12, polyvinylpynolidone Ki 7, polyvinylpyrrolidone K25, or polyvinylpyrrolidone K30, vinyl pynolidone/vinyl acetate copolymer (S630), sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose (hypromellose), hydroxymethylcellulose acetate stearate, polysorbate-80, hydroxyethylcellulose, sodium alginate, gums, such as, e.g., gum tragacanth and gum acacia, guar gum, xanthans, including xanthan gum, sugars, cellulosics, such as, e.g., sodium carboxymethylcellulose, methylcellulose, sodium carboxymethylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, polysorbate-80, sodium alginate, polyethoxylated sorbitan monolaurate, polyethoxylated sorbitan monolaurate, povidone and the like. In some embodiments, useful aqueous suspensions also contain one or more polymers as suspending agents. Useful polymers include water-soluble polymers such as cellulosic polymers, e.g., hydroxypropyl methylcellulose, and water-insoluble polymers such as cross-linked carboxyl-containing polymers.

1001031 In some embodiments, a composition disclosed herein comprises hydroxyethyl cellulose. Hydroxyethyl cellulose (HEC) is obtained as a dry powder which can be reconstituted in water or an aqueous buffer solution to give the desired viscosity (generally about 200 cps to about 30,000 cps, corresponding to about 0.2 to about 10% HEC). In some embodiments, the concentration of HEC is between about 1% and about 15%, about 1% and about 2%, or about 1.5% to about 2%.

Stabilizers 1001041 In some embodiments, a formulation disclosed herein comprises a stabilizing agent. In some embodiments, a formulation disclosed herein comprises a cyclodextrin. Cyclodextrins are cyclic oligosaccharides containing 6, 7, or 8 glucopyranose units, referred to as a-cyclodextrin, -cyclodextrin, or y-cyclodextrin respectively. Cyclodextrins have a hydrophilic exterior, which enhances water-solubility, and a hydrophobic interior which forms a cavity. In an aqueous environment, hydrophobic portions of other molecules often enter the hydrophobic cavity of cyclodextrin to form inclusion compounds. Additionally, cyclodextrins are also capable of other types of nonbonding interactions with molecules that are not inside the hydrophobic cavity. Cyclodextrins have three free hydroxyl groups for each glucopyranose unit, or 18 hydroxyl groups on a-cyclodextrin, 21 hydroxyl groups on -cyclodextrin, and 24 hydroxyl groups on y-cyclodextrin. One or more of these hydroxyl groups can be reacted with any of a number of reagents to form a large variety of cyclodextrin derivatives, including hydroxypropyl ethers, sulfonates, and sulfoalkylethers. Shown below is the structure of -cyclodextrin and the hydroxypropyI--cyclodextrin (HPCD).

R * H RO 3-cycIodextrin RO-'v1 0 \OR RO \ R = CH2CH(OH)CH3 9DR hydroxypropyl 13-cyclodextrin

OR

0 OR R.. 0 o

RO

OR

1001051 In some embodiments, the use of a cyclodextrin in the pharmaceutical compositions described herein improves the solubility of the drug. Inclusion compounds are involved in many cases of enhanced solubility; however other interactions between cyclodextrins and insoluble compounds also improve solubility.

Hydroxypropyl--cyc1odextrin (HPCD) is commercially available as a pyrogen free product. It is a nonhygroscopic white powder that readily dissolves in water. HPCD is thermally stable and does not degrade at neutral pH. Thus, cyclodextrins improve the solubility of a therapeutic agent in a composition or formulation.

Accordingly, in some embodiments, cyclodextrins are included to increase the solubility of an NMDA receptor antagonist within the compositions described herein.

1001061 By way of example only, cyclodextrin derivatives for use include c-cyclodextrin, -cyclodextrin, y- cyclodextrin, hydroxyethyl -cyclodextrin, hydroxypropyl y-cyclodextrin, sulfated -cyclodextrin, sulfated a-cyclodextrin, sulfobutyl ether -cyclodextrin.

1001071 The concentration of the cyclodextrin used in the compositions and methods disclosed herein varies according to the physiochemical properties, pharmacokinetic properties, side effect or adverse events, formulation considerations, or other factors associated with the therapeutically active agent, or a salt or prodrug thereof, or with the properties of other excipients in the composition. Thus, in certain circumstances, the concentration or amount of cyclodextrin used in accordance with the compositions and methods disclosed herein will vary, depending on the need. When used, the amount of cyclodextrins needed to increase solubility of an NMDA receptor antagonist and/or function as a controlled release excipient in any of the formulations described herein is selected using the principles, examples, and teachings described herein.

1001081 Other stabilizers that are useful in the auris-acceptable formulations disclosed herein include, for example, fatty acids, fatty alcohols, alcohols, long chain fatty acid esters, long chain ethers, hydrophilic derivatives of fatty acids, polyvinyl pyrrolidones, polyvinyl ethers, polyvinyl alcohols, hydrocarbons, hydrophobic polymers, moisture-absorbing polymers, and combinations thereof. In some embodiments, amide analogues of stabilizers are also used. In further embodiments, the chosen stabilizer changes the hydrophobicity of the formulation (e.g., oleic acid, waxes), or improves the mixing of various components in the formulation (e.g., ethanol), controls the moisture level in the formula (e.g., PVP or polyvinyl pyrrolidone), controls the mobility of the phase (substances with melting points higher than room temperature such as long chain fatty acids, alcohols, esters, ethers, amides etc. or mixtures thereof; waxes), and/or improves the compatibility of the formula with encapsulating materials (e.g., oleic acid or wax). In another embodiment some of these stabilizers are used as solvents/co-solvents (e.g., ethanol). In other embodiments, stabilizers are present in sufficient amounts to inhibit the degradation of an NMDA receptor antagonist. Examples of such stabilizing agents, include, but are not limited to: (a) about 0.5% to about 2% w/v glycerol, (b) about 0.1% to about 1% w/v methionine, (c) about 0.1% to about 2% w/v monothioglycerol, (d) about 1 mM to about 10mM EDTA, (e) about 0.01% to about 2% w/v ascorbic acid, (f) 0.003% to about 0.02% w/v polysorbate 80, (g) 0.00 1% to about 0.05% w/v. polysorbate 20, (h) arginine, (i) heparin, (j) dextran sulfate, (k) cyclodextrins, (I) pentosan polysulfate and other heparinoids, (m) divalent cations such as magnesium and zinc; or (n) combinations thereof.

1001091 In some embodiements, a compositin disclosed herein comprises an anti-aggregation additive. The anti-aggregation additive selected depends upon the nature of the conditions to which an NMDA receptor antagonist, for example the FNKITAT protein construct, is exposed. For example, certain formulations undergoing agitation and thermal stress require a different anti-aggregation additive than a formulation undergoing lyophilization and reconstitution. Useful anti-aggregation additives include, by way of example only, urea, guanidinium chloride, simple amino acids such as glycine or arginine, sugars, polyalcohols, polysorbates, polymers such as polyethylene glycol and dextrans, alkyl saccharides, such as alkyl glycoside, and surfactants.

1001101 In some embodiements, a compositin disclosed herein comprises an antioxidant. Suitable antioxidants include, by way of example only, ascorbic acid, methionine, sodium thiosulfate and sodium metabisulfite. In some embodiments, antioxidants are selected from metal chelating agents, thiol containing compounds and other general stabilizing agents.

1001111 In some embodiments, a composition disclosed herein is stable with respect to compound degradation over a period of any of at least about 1 day, at least about 2 days, at least about 3 days, at least about 4 days, at least about 5 days, at least about 6 days, at least about 1 week, at least about 2 weeks, at least about 3 weeks, at least about 4 weeks, at least about S weeks, at least about 6 weeks, at least about 7 weeks, at least about 8 weeks, at least about 3 months, at least about 4 months, at least about S months, or at least about 6 months. In other embodiments, the formulations described herein are stable with respect to compound degradation over a period of at least about 1 week. Also described herein are formulations that are stable with respect to compound degradation over a period of at least about 1 month.

Preservatives 1001121 In some embodiments, a composition disclosed herein comprises a preservative. Suitable auris-acceptable preservatives for use in a composition disclosed herein include, but are not limited to benzoic acid, boric acid, p-hydroxybenzoates, alcohols, quaternary compounds, stabilized chlorine dioxide, mercurials, such as merfen and thiomersal, mixtures of the foregoing and the like. Suitable preservatives for use with a formulation disclosed herein are not ototoxic. In some embodiments, a formulation disclosed herein does not include a preservative that is ototoxic. In some embodiments, a formulation disclosed herein does not include benzalkonium chloride or benzethonium chloride.

1001131 In a further embodiment, the preservative is, by way of example only, an antimicrobial agent. In some embodiments, a composition disclosed herein comprises a preservative such as methylparaben. In some embodiments, the methylparaben is at a concentration of about 0.05% to about 1.0%, about 0.1% to about 0.2%.

In some embodiments, a composition comprising an NMDA receptor antagonist is prepared by mixing water, methylparaben, hydroxyethylcellulose and sodium citrate. In some embodiments, a composition comprising an NMDA receptor antagonist is prepared by mixing water, methylparaben, hydroxyethylcellulose and sodium acetate. In some embodiments, a composition disclosed herein is sterilized by autoclaving at 120 °C for about 20 minutes, and tested for pH, methylparaben concentration and viscosity before mixing with the appropriate amount of an NMDA receptor antagonist.

A uris-Acceptable Gels 1001141 Provided herein are NMDA receptor antagonist compositions that ameliorate or lessen otic disorders characterized by loss of a plurality of cells (e.g., hair cell, or neurons). Further provided herein are methods comprising the administration of said NMDA receptor antagonist compositions. In some embodiments, the compositions are formulated as gels. All of the components of the gel formulation must be compatible with the targeted auris structure.

1001151 The terms "gel formulation," "auris acceptable gel formulations," "auris interna-acceptable gel formulations," "auris media-acceptable gel formulations," "auris externa-acceptable gel formulations", "auris gel formulations" or variations thereof are used interchangeably.

1001161 Gels, sometimes referred to as jellies, have been defined in various ways. For example, the United States Pharmacopoeia defines gels as semisolid systems consisting of either suspensions made up of small inorganic particles or large organic molecules interpenetrated by a liquid. Gels include a single-phase or a two-phase system. A single-phase gel consists of organic macromolecules distributed uniformly throughout a liquid in such a manner that no apparent boundaries exist between the dispersed macromolecules and the liquid. Some single-phase gels are prepared from synthetic macromolecules (e.g., carbomer) or from natural gums, (e.g., tragacanth).

In some embodiments, single-phase gels are generally aqueous, but will also be made using alcohols and oils.

Two-phase gels consist of a network of small discrete particles.

1001 171 Gels can also be classified as being hydrophobic or hydrophilic. In certain embodiments, the base of a hydrophobic gel consists of a liquid paraffin with polyethylene or fatty oils gelled with colloidal silica, or aluminum or zinc soaps. In contrast, the base of hydrophobic gels usually consists of water, glycerol, or propylene glycol gelled with a suitable gelling agent (e.g., tragacanth, starch, cellulose derivatives, carboxyvinylpolymers, and magnesium-aluminum silicates). In certain embodiments, the rheology of the compositions disclosed herein is pseudo plastic, plastic, thixotropic, or dilatant.

1001181 In some embodiments the enhanced viscosity auns-acceptable formulation described herein is not a liquid at room temperature. In certain embodiments, the enhanced viscosity formulation is characterized by a phase transition between room temperature and body temperature. In some embodiments, the phase transition occurs at 1 °C below body temperature, at 2 °C below body temperature, at 3 °C below body temperature, at 4 °C below body temperature, at 6 °C below body temperature, at 8 °C below body temperature, or at 10 °C below body temperature.

1001191 Polymers composed of polyoxypropylene and polyoxyethylene form thermoreversible gels when incorporated into aqueous solutions. These polymers have the ability to change from the liquid state to the gel state at temperatures close to body temperature, therefore allowing useful formulations that are applied to the targeted auris structure(s). The liquid state-to-gel state phase transition is dependent on the polymer concentration and the ingredients in the solution.

1001201 Poloxamer 407 (PF-127) is a nonionic surfactant composed of polyoxyethylene-polyoxypropylene copolymers. Other poloxamers include 188 (F-68 grade), 237 (F-87 grade), 338 (F-108 grade). Aqueous solutions of poloxamers are stable in the presence of acids, alkalis, and metal ions. PF-127 is a commercially available polyoxyethylene-polyoxypropylene triblock copolymer of general formula El 06 P70 El 06, with an average molar mass of 13,000. It contains approximately 70% ethylene oxide, which accounts for its hydrophilicity. It is one of the series of poloxamer ABA block copolymers, whose members share the chemical formula shown below.

hydrophilic hydrophilic HO-CH2-cH2XO_CH-CH2}(O_CHCH2)-OH hydrophobic In an alternative embodiment, the thermogel is a PEG-PLGA-PEG triblock copolymer (Jeong et al, Nature (1997), 388:860-2; Jeong et al, J. Control. Release (2000), 63:155-63; Jeong et al, Adv. Drug Delivery Rev.

(2002), 54:37-51). The polymer exhibits sol-gel behavior over a concentration of about 5% w/w to about 40% w/w. Depending on the properties desired, the lactide/glycolide molar ratio in the PLGA copolymer ranges from about 1:1 to about 20:1. The resulting coploymers are soluble in water and form a free-flowing liquid at room temperature, but form a hydrogel at body temperature. A commercially available PEG-PLGA-PEG triblock copolymer is RESOMER RGP tSO 106 manufactured by Boehringer Ingelheim. This material is composed of a PGLA copolymer of 50:50 poly(DL-lactide-co-glycolide) and is 10% w/w of PEG and has a molecular weight of about 6000.

1001211 ReGel� is a tradename of MacroMed Incorporated for a class of low molecular weight, biodegradable block copolymers having reverse thermal gelation properties as described in U.S. Pat. Nos. 6,004,573, 6,117949, 6,201,072, and 6,287,588. It also includes biodegradable polymeric drug carriers disclosed in pending U.S. patent application Ser. Nos. 09/906,041, 09/559,799 and 10/919,603. The biodegradable drug carrier comprises ABA-type or BAB-type triblock copolymers or mixtures thereof, wherein the A-blocks are relatively hydrophobic and comprise biodegradable polyesters or poly(orthoester)s, and the B-blocks are relatively hydrophilic and comprise polyethylene glycol (PEG), said copolymers having a hydrophobic content of between 50.1 to 83% by weight and a hydrophilic content of between 17 to 49.9% by weight, and an overall block copolymer molecular weight of between 2000 and 8000 Daltons. The drug carriers exhibit water solubility at temperatures below normal mammalian body temperatures and undergo reversible thermal gelation to then exist as a gel at temperatures equal to physiological mammalian body temperatures. The biodegradable, hydrophobic A polymer block comprises a polyester or poly(ortho ester), in which the polyester is synthesized from monomers selected from the group consisting of D,L-lactide, D-lactide, L-lactide, D,L-lactic acid, D-lactic acid, L-lactic acid, glycolide, glycolic acid, -caprolactone, -hydroxyhexanoic acid, y-butyrolactone, y-hydroxybutyric acid, -valerolactone, -hydroxyvaleric acid, hydroxybutyric acids, malic acid, and copolymers thereof and having an average molecular weight of between about 600 and 3000 Daltons. The hydrophilic B-block segment is preferably polyethylene glycol (PEG) having an average molecular weight of between about 500 and 2200 Daltons.

1001221 Additional biodegradable thermoplastic polyesters include AtriGel� (provided by Atrix Laboratories, Inc.) and/or those disclosed, e.g., in U.S. Patent Nos. 5,324,519; 4,938,763; 5,702,716; 5,744,153; and 5,990,194; wherein the suitable biodegradable thermoplastic polyester is disclosed as a thermoplastic polymer. Examples of suitable biodegradable thermoplastic polyesters include polylactides, polyglycolides, polycaprolactones, copolymers thereof, terpolymers thereof, and any combinations thereof. In some such embodiments, the suitable biodegradable thermoplastic polyester is a polylactide, a polyglycolide, a copolymer thereof, a terpolymer thereof, or a combination thereof. In some embodiments, the biodegradable thermoplastic polyester is 50/50 poly(DL-lactide-co-glycolide) having a carboxy terminal group; is present in about 30 wt. % to about 40 wt. % of the composition; and has an average molecular weight of about 23,000 to about 45,000. Alternatively, in another embodiment, the biodegradable thermoplastic polyester is 75/25 poly (DL-lactide-co-glycolide) without a carboxy terminal group; is present in about 40 wt. % to about 50 wt. % of the composition; and has an average molecular weight of about 15,000 to about 24,000. In further or alternative embodiments, the terminal groups of the poly(DL-lactide-co-glycolide) are either hydroxyl, carboxyl, or ester depending upon the method of polymerization. Polycondensation of lactic or glycolic acid provides a polymer with terminal hydroxyl and carboxyl groups. Ring-opening polymerization of the cyclic lactide or glycolide monomers with water, lactic acid, or glycolic acid provides polymers with the same terminal groups. However, ring-opening of the cyclic monomers with a monofunctional alcohol such as methanol, ethanol, or 1 -dodecanol provides a polymer with one hydroxyl group and one ester terminal groups. Ring-opening polymerization of the cyclic monomers with a diol such as 1,6-hexanediol or polyethylene glycol provides a polymer with only hydroxyl terminal groups.

1001231 Since the polymer systems of thermoreversible gels dissolve more completely at reduced temperatures, methods of solubilization include adding the required amount of polymer to the amount of water to be used at reduced temperatures. Generally after wetting the polymer by shaking, the mixture is capped and placed in a cold chamber or in a thermostatic container at about 0-10 °C in order to dissolve the polymer. The mixture is stirred or shaken to bring about a more rapid dissolution of the thermoreversible gel polymer. The corticosteroid and various additives such as buffers, salts, and preservatives are subsequently added and dissolved. In some instances the corticosteroid and/or other pharmaceutically active agent is suspended if it is insoluble in water. The pH is modulated by the addition of appropriate buffering agents. round window membrane mucoadhesive characteristics are optionally imparted to a thermoreversible gel by incorporation of round window membrane mucoadhesive carbomers, such as Carbopol� 934P, to the composition (Majithiya et al, AAPS PharmSciTech (2006), 7(3), p. El; EPOSS 1626, both of which is incorporated herein by reference for such disclosure).

1001241 In some embodiments are auris-acceptable pharmaceutical gel formulations which do not require the use of an added viscosity enhancing agent. Such gel formulations incorporate at least one pharmaceutically acceptable buffer. In one aspect is a gel formulation comprising an corticosteroid and a pharmaceutically acceptable buffer.

In another embodiment, the pharmaceutically acceptable excipient or carrier is a gelling agent.

Radiation Curable Gels 1001251 In some embodiments, a composition disclosed herein is an actinic radiation curable gel. In some embodiments, exposure to actinic radiation (or light, including UV light, visible light, or infrared light) results in the desired gel properties being formed. By way of example only, fiber optics are used to provide the actinic radiation so as to form the desired gel properties. In some embodiments, the fiber optics and the gel administration device form a single unit. In other embodiments, the fiber optics and the gel administration device are provided separately.

Solvent Release Gels 1001261 In some embodiments, a composition disclosed herein is a solvent release gel. In some embodiments, a gel having the desired gel properties is formed as a solvent drom of the composition. For example, a formulation that comprises sucrose acetate isobutyrate, a pharmaceutically acceptable solvent, one or more additives, and the auris-acceptable NMDA receptor antagonist is administered at or near the round window membrane: diffusion of the solvent out of the injected formulation provides a depot having the desired gel properties. For example, use of a water soluble solvent provides a high viscosity depot when the solvent diffuses rapidly out of the injected formulation. On the other hand, use of a hydrophobic solvent (e.g., benzyl benzoate) provides a less viscous depot. One example of an auris-acceptable solvent release gel formulation is the SABERTM Delivery System marketed by DURECT Corporation.

Lzosomes 1001271 In some embodiments, liposomes or lipid particles are employed to encapsulate a composition disclosed herein. Phospholipids that are gently dispersed in an aqueous medium form multilayer vesicles with areas of entrapped aqueous media separating the lipid layers. Sonication, or turbulent agitation, of these multilayer veiscles results in the formation of single layer vesicles, commonly refered to as liposomes, with sizes of about 10-1000 nm. These liposomes have many advantages as carriers. They are biologically inert, biodegradable, non-toxic and non-antigenic. Liposomes are formed in various sizes and with varying compositions and surface properties. Additionally, they are able to entrap a wide variety of agents and release the agent at the site of liposome collapse.

1001281 Suitable phospholipids for use in a composition disclosed herein include, but are not limited to, phosphatidyl cholines, ethanolamines and serines, sphingomyelins, cardiolipins, plasmalogens, phosphatictic acids and cerebrosides, in particular those which are soluble together with the corticosteroids herein in non-toxic, pharmaceutically acceptable organic solvents. Preferred phospholipids are, for example, phosphatidyl choline, phosphatidyl ethanolmine, phosphatidyl serine, phosphatidyl inositol, lysophosphatidyl choline, phosphatidyl glycerol and the like, and mixtures thereof especially lecithin, e.g. soya lecithin. The amount of phospholipid used in the present formulation range from about 10 to about 30%, preferably from about 15 to about 25% and in particular is about 20%.

1001291 Lipophilic additives may be employed advantageously to modifj selectively the characteristics of the liposomes. Examples of such additives include by way of example only, stearylamine, phosphatictic acid, tocopherol, cholesterol, cholesterol hemisuccinate and lanolin extracts. The amount of lipophilic additive used ranges from 0.5 to 8%, preferably from 1.5 to 4% and in particular is about 2%. Generally, the ratio of the amount of lipophilic additive to the amount of phospholipid ranges from about 1:8 to about 1:12 and in particular is about 1:10.

1001301 In some embodiments, a composition disclosed herein further comprises a solvent capable of disolving one or more components of the composition. In some embodiments, the solvent dissolves an NMDA receptor antagonist and allows the formulation of stable single bilayered liposomes. In some embodiments, the solvent comprises dimethylisosorbide and tetraglycol (glycofurol, tetrahydrofurfuryl alcohol polyethylene glycol ether) in an amount of about 8 to about 30%. In some embodiments, the ratio of the amount of dimethylisosorbide to the amount of tetraglycol range from about 2:1 to about 1:3, in particular from about 1:1 to about 1:2.5 and preferably is about 1:2. In some embodiments, the amount of tetraglycol in the final composition is from about S to about 20%, in particular from about S to about 15% and preferably is approximately 10%. In some embodiments, the amount of dimethylisosorbide in the composition ranges from about 3 to about 10%, in particular from about 3 to about 7% and preferably is approximately 5%.

1001311 The term "organic component" as used hereinafter refers to mixtures comprising said phospholipid, lipophilic additives and organic solvents. In some embodiments, an NMDA receptor antagonist is dissolved in the organic component, or other means to maintain full activity of the agent. In some embodiments, the amount of an NMDA receptor antagonist in the final formulation may range from 0.1 to 5.0%. In some embodiments, additional components such as anti-oxidants are added to the organic component. Examples of additional components include, but are not limited to, tocopherol, butylated hydroxyanisole, butylated hydroxytoluene, ascorbyl palmitate, ascorbyl oleate and the like.

Paints 1001321 In some embodiments, a composition disclosed herein is formulated as an auris-acceptable paint. As used herein, paints (also Imown as film formers) are solutions comprisinf a solvent, a monomer or polymer, an active agent, and optionally one or more pharmaceutically-acceptable excipients. In some embodiments, after application to a tissue, the solvent evaporates leaving behind a thin coating comprised of the monomers or polymers, and the active agent. In some embodiments, the coating protects active agents and maintains them in an immobilized state at the site of application. In some embodiments, the presence of a protective coating decreases the amount of active agent which may be lost and correspondingly increases the amount delivered to the subject.

By way of non-limiting example, paints include collodions (e.g. Flexible Collodion, USP), and solutions comprising saccharide siloxane copolymers and a cross-linking agent. Collodions are ethyl ether/ethanol solutions containing pyroxylin (a nitrocellulose). After application, the ethyl ether/ethanol solution evaporates leaving behind a thin film of pyroxylin. In solutions comprising saccharide siloxane copolymers, the saccharide siloxane copolymers form the coating after evaporation of the solvent initiates the cross-linking of the saccharide siloxane copolymers. For additional disclosures regarding paints, see Rem ington. The Science and Practice of Pharmacy which is hereby incorporated for this subject matter. The paints contemplated for use herein, are flexible such that they do not interfere with the propagation of pressure waves through the ear. In some embodiments, the paints are applied as a liquid (i.e. solution, suspension, or emulsion), a semisolid (i.e. a gel, foam, paste, or jelly) or an aerosol. Foams

1001331 In some embodiments, a composition disclosed herein is formulated as a foam. Examples of suitable foamable carriers for use in the compositions disclosed herein include, but are not limited to, alginate and derivatives thereof, carboxymethylcellulose and derivatives thereof, collagen, polysaccharides, including, for example, dextran, dextran derivatives, pectin, starch, modified starches such as starches having additional carboxyl and/or carboxamide groups and/or having hydrophilic side-chains, cellulose and derivatives thereof, agar and derivatives thereof, such as agar stabilised with polyacrylamide, polyethylene oxides, glycol methacrylates, gelatin, gums such as xanthum, guar, karaya, gellan, arabic, tragacanth and locust bean gum, or combinations thereof. Also suitable are salts of the aforementioned carriers, for example, sodium alginate. The formulation optionally further comprises a foaming agent, which promotes the formation of the foam, including a surfactant or external propellant. Examples of suitable foaming agents include cetrimide, lecithin, soaps, silicones and the like.

Commercially available surfactants such as Tween� are also suitable.

Controlled Release Compositions 1001341 Provided herein are NMDA receptor antagonist compositions that ameliorate or lessen otic disorders characterized by loss of a plurality of cells (e.g., hair cell, or neurons). Further provided herein are methods comprising the administration of said NMDA receptor antagonist compositions. In some embodiments, the compositions are controlled-release compositions. In general, controlled release drug formulations impart control over the release of drug with respect to site of release and time of release within the body. As used herein, controlled release refers to immediate release, delayed release, sustained release, extended release, variable release, pulsatile release and bi-modal release. Many advantages are offered by controlled release. First, controlled release of a pharmaceutical agent allows less frequent dosing and thus minimizes repeated treatment.

Second, controlled release treatment results in more efficient drug utilization and less of the compound remains as a residue. Third, controlled release offers the possibility of localized drug delivery by placement of a delivery device or formulation at the site of disease. Still further, controlled release offers the opportunity to administer and release two or more different drugs, each having a unique release profile, or to release the same drug at different rates or for different durations, by means of a single dosage unit.

1001351 Thus, by providing a a controlled release NMDA receptor antagonist composition to treat otic disorders, a constant, variable and/or extended source of an NMDA receptor antagonist is provided to the individual or patient suffering from an otic disorder, reducing or eliminating the variability of treatment. Accordingly, one embodiment disclosed herein is to provide a formulation that enables at least one an NMDA receptor antagonist to be released in therapeutically effective doses either at variable or constant rates such as to ensure a continuous release of the at least one agent. In some embodiments, a composition disclosed herein is formulated for immediate release. In some embodiments, a composition disclosed herein is formulated for sustained release (e.g., continuously, variably or in a pulsatile manner, or variants thereof). In some embodiments, a composition disclosed herein is formulated for immediate release and sustained release.

1001361 In some embodiments, a composition disclosed herein is formulated such that an NMDA receptor antagonist is released from the composition over a period of 3 days. In some embodiments, a composition disclosed herein is formulated such that an NMDA receptor antagonist is released from the composition over a period of 4 days. In some embodiments, a composition disclosed herein is formulated such that an NMDA receptor antagonist is released from the composition over a period of 5 days. In some embodiments, a composition disclosed herein is formulated such that an NMDA receptor antagonist is released from the composition over a period of 7 days. In some embodiments, a composition disclosed herein is formulated such that an NMDA receptor antagonist is released from the composition over a period of 10 days. In some embodiments, a composition disclosed herein is formulated such that an NMDA receptor antagonist is released from the composition over a period of 14 days. In some embodiments, a composition disclosed herein is formulated such that an NMDA receptor antagonist is released from the composition over a period of 21 days. In some embodiments, a composition disclosed herein is formulated such that an NMDA receptor antagonist is released from the composition over a period of one month.

1001371 In some embodiments, an NMDA receptor antagonist disclosed herein is incorporated within controlled release particles, lipid complexes, liposomes, nanoparticles, microspheres, microparticles, nanocapsules or other agents which enhance or facilitate the localized delivery of the NMDA receptor antagonist. In some embodiments, a single enhanced viscosity formulation is used, in which at least one an NMDA receptor antagonist is present, while in other embodiments, a pharmaceutical formulation that comprises a mixture of two or more distinct enhanced viscosity formulations is used, in which at least one an NMDA receptor antagonist is present. In some embodiments, combinations of sols, gels and/or biocompatible matrices is also employed to provide desirable characteristics of the controlled release an NMDA receptor antagonist compositions or formulations. In certain embodiments, a composition disclosed herein is cross-linked by one or more agents to alter or improve the properties of the composition.

1001381 Examples of microspheres relevant to the pharmaceutical formulations disclosed herein include: Luzzi, L. A., J. Pharm. Psy. 59:1367 (1970); U.S. Pat. No. 4,530,840; Lewis, D. H., "Controlled Release of Bioactive Agents from Lactides/Glycolide Polymers" in Biodegradable Polymers as Drug Delivery Systems, Chasm M. and Langer, R., eds., Marcel Decker (1990); U.S. Pat. No. 4,675,189; Beck et al., "Poly(lactic acid) and Poly(lactic acid-co-glycolic acid) Contraceptive Delivery systems," in Long Acting 5teroid Contraception, Mishell, D. R., ed., Raven Press (1983); U.s. Pat. No. 4,758,435; U.s. Pat. No. 3,773,919; U.s. Pat. No. 4,474,572. Examples of protein therapeutics formulated as microspheres include: U.S. Pat. No. 6,458,387; U.s. Pat. No. 6,268,053; U.s.

Pat. No. 6,090,925; U.S. Pat. No. 5,981,719; and U.S. Pat. No. 5,578,709, and are herein incorporated by

reference for such disclosure.

1001391 Microspheres usually have a spherical shape, although irregularly-shaped microparticles are possible.

Microspheres may vary in size, ranging from submicron to 1000 micron diameters. Microspheres suitable for use with the auris-acceptable formulations disclosed herein are submicron to 250 micron diameter microspheres, allowing administration by injection with a standard gauge needle. The auris-acceptable microspheres can thus be prepared by any method which produces microspheres in a size range acceptable for use in an injectable composition. Injection is optionally accomplished with standard gauge needles used for administering liquid compositions.

1001401 Suitable examples of polymeric matrix materials for use in the auns-acceptable controlled release particles herein include poly(glycolic acid), poly-d,l-lactic acid, poly-l-lactic acid, copolymers of the foregoing, poly(aliphatic carboxylic acids), copolyoxalates, polycaprolactone, polydioxonene, poly(orthocarbonates), poly(acetals), poly(lactic acid-caprolactone), polyorthoesters, poly(glycolic acid-caprolactone), polydioxonene, polyanhydrides, polyphosphazines, and natural polymers including albumin, casein, and some waxes, such as, glycerol mono-and distearate, and the like. Various commercially available poly (lactide-co-glycolide) materials (PLGA) are optionally used in the method disclosed herein. For example, poly (d,l-lactic-co-glycolic acid) is commercially available from Boehringer-Jngelheim as ResomerTM RG 503 H. This product has a mole percent composition of 50% lactide and 50% glycolide. These copolymers are available in a wide range of molecular weights and ratios of lactic acid to glycolic acid. One embodiment includes the use of the polymer poly(d,l-lactide-co-glycolide). The molar ratio of lactide to glycolide in such a copolymer includes the range of from about 95:5 to about 50:50.

1001411 The molecular weight of the polymeric matrix material is of some importance. The molecular weight should be high enough so that it forms satisfactory polymer coatings, i.e., the polymer should be a good film former. Usually, a satisfactory molecular weight is in the range of 5,000 to 500,000 Daltons. The molecular weight of a polymer is also important from the point of view that molecular weight influences the biodegradation rate of the polymer. For a diffusional mechanism of drug release, the polymer should remain intact until all of the drug is released from the microparticles and then degrade. The drug can also be released from the microparticles as the polymeric excipient bioerodes. By an appropriate selection of polymeric materials a microsphere formulation can be made such that the resulting microspheres exhibit both diffusional release and biodegradation release properties. This is useful in affording multiphasic release patterns.

1001421A variety of methods are known by which compounds can be encapsulated in microspheres. In these methods, an NMDA receptor antagonist is generally dispersed or emulsified, using stirrers, agitators, or other dynamic mixing techniques, in a solvent containing a wall-forming material. Solvent is then removed from the microspheres, and thereafter the microsphere product is obtained.

1001431 In some embodiments, a composition disclosed herein is made through the incorporation of an NMDA receptor antagonist into ethylene-vinyl acetate copolymer matrices. (See U.S. Patent No. 6,083,534, incorporated herein for such disclosure). In some embodiments, an NMDA receptor antagonist is incorporated into poly (lactic-glycolic acid) or poly-L-lactic acid microspheres. Id. In some embodiments, an NMDA receptor antagonist is encapsulated into alginate microspheres. (See U.S. Patent No. 6,036,978, incorporated herein for such disclosure).

Biocompatible methacrylate-based polymers to encapsulate an NMDA receptor antagonist is optionally used in the formulations and methods disclosed herein. A wide range of methacrylate-based polmer systems are commerically available, such as the Eudragit� polymers marketed by Evonik. One useful aspect of methacrylate polymers is that the properties of the formulation can be varied by incorporating various co-polymers. For example, poly(acrylic acid-co-methylmethacrylate) microparticles exhibit enhanced mucoadhesion properties as the carboxylic acid groups in the poly(acrylic acid) can form hydrogen bonds with mucin (Park et al., Pharm. Res. (1987) 4(6):457-464). Variation of the ratio between acrylic acid and methylmethacrylate monomers serves to modulate the properties of the co-polymer. Methacrylate-based microparticles have also been used in protein therapeutic formulations (Naha et al., Journal of Microencapsulation 04 February, 2008 (online publication)). In some embodiments, a composition disclosed herein comprises comprises microspheres formed from a methacrylate polymer or copolymer. In some embodiments, the microspheres are mucoadhesive. Other controlled release systems, including incorporation or deposit of polymeric materials or matrices onto solid or hollow spheres containing an NMDA receptor antagonist, is also explicitly contemplated within the embodiments disclosed herein. The types of controlled release systems available without significantly losing activity of an NMDA receptor antagonist is determined using the teachings, examples, and principles disclosed herein.

1001441 An example of a conventional microencapsulation process for pharmaceutical preparations is shown in U.S. Pat. No. 3,737,337, incorporated herein by reference for such disclosure. The NMDA receptor antagonist to be encapsulated or embedded is dissolved or dispersed in the organic solution of the polymer (phase A), using conventional mixers, including (in the preparation of dispersion) vibrators and high-speed stirrers, etc. The dispersion of phase (A), containing the core material in solution or in suspension, is carried out in the aqueous phase (B), again using conventional mixers, such as high-speed mixers, vibration mixers, or even spray nozzles, in which case the particle size of the microspheres will be determined not only by the concentration of phase (A), but also by the emulsate or microsphere size. With conventional techniques for the microencapsulation of an NMDA receptor antagonist, the microspheres form when the solvent containing an active agent and a polymer is emulsified or dispersed in an immiscible solution by stirring, agitating, vibrating, or some other dynamic mixing technique, often for a relatively long period of time.

1001451 Conventional methods for the construction of microspheres are also described in U.S. Pat. No. 4,389,330, and U.S. Pat. No. 4,530,840, incorporated herein by reference for such disclosure. The desired NMDA receptor antagonist is dissolved or dispersed in an appropriate solvent. To the agent-containing medium is added the polymeric matrix material in an amount relative to the active ingredient which gives a product of the desired loading of active agent. Optionally, all of the ingredients of composition are blended in the solvent medium together. Suitable solvents for the agent and the polymeric matrix material include organic solvents such as acetone, halogenated hydrocarbons such as chloroform, methylene chloride and the like, aromatic hydrocarbon compounds, halogenated aromatic hydrocarbon compounds, cyclic ethers, alcohols, ethyl acetate and the like.

1001461 The mixture of ingredients in the solvent is emulsified in a continuous-phase processing medium; the continuous-phase medium being such that a dispersion of micro-droplets containing the indicated ingredients is formed in the continuous-phase medium. Naturally, the continuous-phase processing medium and the organic solvent must be immiscible, and includes water although nonaqueous media such as xylene and toluene and synthetic oils and natural oils are optionally used. Optionally, a surfactant is added to the continuous-phase processing medium to prevent the microparticles from agglomerating and to control the size of the solvent micro-droplets in the emulsion. A preferred surfactant-dispersing medium combination is a 1 to 10 wt. % poly (vinyl alcohol) in water mixture. The dispersion is formed by mechanical agitation of the mixed materials. In some embodiments, an emulsion is formed by adding small drops of the active agent-wall forming material solution to the continuous phase processing medium. The temperature during the formation of the emulsion is not especially critical but can influence the size and quality of the microspheres and the solubility of the drug in the continuous phase. It is desirable to have as little of the agent in the continuous phase as possible. Moreover, depending on the solvent and continuous-phase processing medium employed, the temperature must not be too low or the solvent and processing medium will solidify or the processing medium will become too viscous for practical purposes, or too high that the processing medium will evaporate, or that the liquid processing medium will not be maintained.

Moreover, the temperature of the medium cannot be so high that the stability of the particular agent being incorporated in the microspheres is adversely affected. Accordingly, in some embodiments, the dispersion process is conducted at a temperature which maintains stable operating conditions, which preferred temperature being about 15 °C to 60 °C, depending upon the drug and excipient selected.

1001471 In some embodiments, the dispersion which is formed is a stable emulsion and from this dispersion the organic solvent immiscible fluid is optionally partially removed in the first step of the solvent removal process.

The solvent is removed by any suitable technique (e.g., heating, the application of a reduced pressure or a combination of both). The temperature employed to evaporate solvent from the micro-droplets is not critical, but should not be so high that it degrades the NMDA receptor antagonist employed in the preparation of a given micro-particle, nor should it be so high as to evaporate solvent at such a rapid rate to cause defects in the wall forming material. Generally, from S to 75%, of the solvent is removed in the first solvent removal step.

1001481 After the first stage, the dispersed microparticles in the solvent immiscible fluid medium are isolated from the fluid medium by any convenient means of separation. In some embodiments, the fluid is decanted from the microspheres. In some embodiments, the microsphere suspension is filtered. Still other, various combinations of separation techniques can be used if desired.

1001491 Following the isolation of the microspheres from the continuous-phase processing medium, the remainder of the solvent in the microspheres is removed by extraction. In some embodiments, the microspheres are suspended in the same continuous-phase processing medium used in step one, with or without surfactant, or in another liquid. The extraction medium removes the solvent from the microspheres and yet does not dissolve the microspheres. During the extraction, in some embodiments, the extraction medium with dissolved solvent is removed and replaced with fresh extraction medium. This is best done on a continual basis. The rate of extraction medium replenishment of a given process is a variable that is determined at the time the process is performed and, therefore, no precise limits for the rate must be predetermined. After the majority of the solvent has been removed from the microspheres, the microspheres are dried by exposure to air or by other conventional drying techniques such as vacuum drying, drying over a desiccant, or the like. This process is very efficient in encapsulating the NMDA receptor antagonist since core loadings of up to 80 wt. %, preferably up to 60 wt. % are obtained.

1001501 Alternatively, controlled release microspheres containing an NMDA receptor antagonist are prepared through the use of static mixers. Static or motionless mixers consist of a conduit or tube in which is received a number of static mixing agents. Static mixers provide homogeneous mixing in a relatively short length of conduit, and in a relatively short period of time. With static mixers, the fluid moves through the mixer, rather than some part of the mixer (for example, a blade) moving through the fluid.

1001511 In some embodiments, a static mixer is used to create an emulsion. When using a static mixer to form an emulsion, several factors determine emulsion particle size, including the density and viscosity of the various solutions or phases to be mixed, volume ratio of the phases, interfacial tension between the phases, static mixer parameters (conduit diameter; length of mixing element; number of mixing elements), and linear velocity through the static mixer. Temperature is a variable because it affects density, viscosity, and interfacial tension. The controlling variables are linear velocity, sheer rate, and pressure drop per unit length of static mixer.

1001521 In order to create microspheres containing an NMDA receptor antagonist using a static mixer process, an organic phase and an aqueous phase are combined. The organic and aqueous phases are largely or substantially immiscible, with the aqueous phase constituting the continuous phase of the emulsion. The organic phase includes an NMDA receptor antagonist as well as a wall-forming polymer or polymeric matrix material. In some embodiments, the organic phase is prepared by dissolving an NMDA receptor antagonist in an organic or other suitable solvent, or by forming a dispersion or an emulsion containing the NMDA receptor antagonist. The organic phase and the aqueous phase are pumped so that the two phases flow simultaneously through a static mixer, thereby forming an emulsion which comprises microspheres containing the NMDA receptor antagonist encapsulated in the polymeric matrix material. The organic and aqueous phases are pumped through the static mixer into a large volume of quench liquid to extract or remove the organic solvent. Organic solvent is optionally removed from the microspheres while they are washing or being stirred in the quench liquid. After the microspheres are washed in a quench liquid, they are isolated, as through a sieve, and dried.

1001531 In some embodiments, microspheres are prepared using a static mixer can be carried out for a variety of techniques used to encapsulate active agents. The process is not limited to the solvent extraction technique discussed above, but can be used with other encapsulation techniques. In some embodiments, the process is used with a phase separation encapsulation technique. To do so, an organic phase is prepared that comprises an NMDA receptor antagonist suspended or dispersed in a polymer solution. The non-solvent second phase is free from solvents for the polymer and active agent. A preferred non-solvent second phase is silicone oil. The organic phase and the non-solvent phase are pumped through a static mixer into a non-solvent quench liquid, such as heptane.

The semi-solid particles are quenched for complete hardening and washing. The process of microencapsulation includes spray drying, solvent evaporation, a combination of evaporation and extraction, and melt extrusion.

1001541 In another embodiment, the microencapsulation process involves the use of a static mixer with a single solvent. This process is described in detail in U.S. application Ser. No. 08/338,805, herein incorporated by reference for such disclosure. An alternative process involves the use of a static mixer with co-solvents. In this process, biodegradable microspheres comprising a biodegradable polymeric binder and an NMDA receptor antagonist are prepared, which comprises a blend of at least two substantially non-toxic solvents, free of halogenated hydrocarbons to dissolve both the agent and the polymer. The solvent blend containing the dissolved agent and polymer is dispersed in an aqueous solution to form droplets. The resulting emulsion is then added to an aqueous extraction medium preferably containing at least one of the solvents of the blend, whereby the rate of extraction of each solvent is controlled, whereupon the biodegradable microspheres containing the pharmaceutically active agent are formed. This process has the advantage that less extraction medium is required because the solubility of one solvent in water is substantially independent of the other and solvent selection is increased, especially with solvents that are particularly difficult to extract.

1001551 Nanoparticles are also contemplated for use with a composition disclosed herein. Nanoparticles are material structures of about 100 nm or less in size. One use of nanoparticles in pharmaceutical formulations is the formation of suspensions as the interaction of the particle surface with solvent is strong enough to overcome differences in density. In some embodiments, nanoparticle suspensions are sterilized as the nanoparticles are small enough to be subjected to sterilizing filtration (see, e.g., U.S. Patent No. 6,139,870, herein incorporated by reference for such disclosure). Nanoparticles comprise at least one hydrophobic, water-insoluble and water-indispersible polymer or copolymer emulsified in a solution or aqueous dispersion of surfactants, phospholipids or fatty acids. The NMDA receptor antagonist is optionally introduced with the polymer or the copolymer into the nanoparticles.

1001561 The use of lipid nanocapsules is also contemplated herein. Lipid nanocapsules are optionally formed by emulsifying capric and caprylic acid triglycerides (LabrafacTM WL 1349; avg. mw 512), soybean lecithin (Lipoid� S75-3; 69% phosphatidylcholine and other phospholipids), surfactant (for example, Solutol� HS 15), a mixture of polyethylene glycol 660 hydroxystearate and free polyethylene glycol 660; NaCI and water. The mixture is stirred at room temperature to obtain an oil emulsion in water. After progressive heating at a rate of 4 °C/min under magnetic stirring, a short interval of transparency should occur close to 70 °C, and the inverted phase (water droplets in oil) obtained at 85 °C. Three cycles of cooling and heating is then applied between 85 °C and 60 °C at the rate of 4 °C/min, and a fast dilution in cold water at a temperature close to 0 °C to produce a suspension of nanocapsules. To encapsulate an NMDA receptor antagonist, the NMDA receptor antagonist is optionally added just prior to the dilution with cold water.

1001571 In some embodiments, an NMDA receptor antagonist is inserted into the lipid nanocapsules by incubation for 90 minutes with an aqueous micellar solution of the auris active agent. The suspension is then vortexed every minutes, and then quenched in an ice bath for 1 minute.

1001581 Suitable surfactants are, by way of example, cholic acid or taurocholic acid salts. Taurocholic acid, the conjugate formed from cholic acid and taurine, is a fully metabolizable sulfonic acid surfactant. An analog of taurocholic acid, tauroursodeoxycholic acid (TUDCA), is a naturally occurring bile acid and is a conjugate of taurine and ursodeoxycholic acid (UDCA). Other naturally occurring anionic (e.g., galactocerebroside sulfate), neutral (e.g., lactosylceramide) or zwitterionic surfactants (e.g., sphingomyelin, phosphatidyl choline, palmitoyl carnitine) are optionally used to prepare nanoparticles.

1001591 The phospholipids are chosen, by way of example, from natural, synthetic or semi-synthetic phospholipids; lecithins (phosphatidylcholine) such as, for example, purified egg or soya lecithins (lecithin El 00, lecithin E80 and phospholipons, for example phospholipon 90), phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, dipalmitoylphosphatidylcholine, dipalmitoylglycerophosphatidylcholine, dimyristoylphosphatidylcholine, distearoylphosphatidylcholine and phosphatidic acid or mixtures thereof are used more particularly.

1001601 Fatty acids for use with a composition disclosed herein are chosen from, by way of example, lauric acid, mysristic acid, palmitic acid, stearic acid, isostearic acid, arachidic acid, behenic acid, oleic acid, myristoleic acid, palmitoleic acid, linoleic acid, alpha-linoleic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosahexaenoic acid, and the like.

1001611 Suitable auris-acceptable surfactants are preferably selected from known organic and inorganic pharmaceutical excipients. Such excipients include various polymers, low molecular weight oligomers, natural products, and surfactants. Preferred surface modifiers include nonionic and ionic surfactants. In some embodiments, two or more surface modifiers are used in combination.

1001621 Representative examples of auris-acceptable surfactants include cetyl pyridinium chloride, gelatin, casein, lecithin (phosphatides), dextran, glycerol, gum acacia, cholesterol, tragacanth, stearic acid, calcium stearate, glycerol monostearate, cetostearyl alcohol, cetomacrogol emulsifying wax, sorbitan esters, polyoxyethylene alkyl ethers, polyoxyethylene castor oil derivatives, polyoxyethylene sorbitan fatty acid esters; dodecyl trimethyl ammonium bromide, polyoxyethylenestearates, colloidal silicon dioxide, phosphates, sodium dodecylsulfate, carboxymethylcellulose calcium, hydroxypropyl cellulose (HPC, HPC-SL, and HPC-L), hydroxypropyl methylcellulose (HPMC), carboxymethylcellulose sodium, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethyl-cellulose phthalate, noncrystalline cellulose, magnesium aluminum silicate, triethanolamine, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), 4-( 1,1,3,3 -tetaamethylbutyl)-phenol polymer with ethylene oxide and formaldehyde (also known as tyloxapol, superione, and triton), poloxamers, poloxamnines, a charged phospholipid such as dimyristoyl phophatidyl glycerol, dioctylsulfosuccinate (DOSS); Tetronic 1508, dialkylesters of sodium sulfosuccinic acid, DuponolTM P, Tritons X- 200, CrodestasTM F-i 10, p-isononylphenoxypoly-(glycidol), Crodestas SL40TM (Croda, Inc.); and SA9OHCO, which is C18 H37 CH2 (CON(CH3)-CH2 (CHOH)4 (CH2 OH)2 (Eastman Kodak Co.); decanoyl-N-methylglucamide; n-decyl J3-D-glucopyranoside; n-decyl 13-D-maltopyranoside; n-dodecyl J3-D-glucopyranoside; n-dodecyl J3-D-maltoside; heptanoyl-N-methylglucamide; n-heptyl-13-D-glucopyranoside; n-heptyl f3-D-thioglucoside; n-hexyl 13-D-glucopyranoside; nonanoyl-N-methylglucamide; n-noyl J3-D-glucopyranoside; octanoyl-N-methylglucarmide; n-octyl-J3-D-glucopyranoside; octyl 3-D-thioglucopyranoside; and the like. Most of these surfactants are known pharmaceutical excipients and are described in detail in the Handbook of Pharmaceutical Excipients, published jointly by the American Pharmaceutical Association and The Pharmaceutical Society of Great Britain (The Pharmaceutical Press, 1986), specifically incorporated by reference

for such disclosure.

1001631 In some embodiments, the hydrophobic, water-insoluble and water-indispersible polymer or copolymer is chosen from biocompatible and biodegradable polymers, for example lactic or glycolic acid polymers and copolymers thereof, or polylactic/polyethylene (or polypropylene) oxide copolymers, preferably with molecular weights of between 1000 and 200,000, polyhydroxybutyric acid polymers, polylactones of fatty acids containing at least 12 carbon atoms, or polyanhydrides.

1001641 In some embodiments, the nanoparticles are obtained by the technique of evaporation of solvent, from an aqueous dispersion or solution of phospholipids and of an oleic acid salt into which is added an immiscible organic phase comprising the active principle and the hydrophobic, water-insoluble and water-indispersible polymer or copolymer. The mixture is pre-emulsified and then subjected to homogenization and evaporation of the organic solvent to obtain an aqueous suspension of very small-sized nanoparticles.

1001651A variety of methods may be employed to fabricate the nanoparticles that are within the scope of the embodiments. These methods include vaporization methods, such as free jet expansion, laser vaporization, spark erosion, electro explosion and chemical vapor deposition; physical methods involving mechanical attrition (e.g., "pearlmilling" technology, Elan Nanosystems), super critical C02 and interfacial deposition following solvent displacement. In some embodiments, the solvent displacement method is used. The size of nanoparticles produced by this method is sensitive to the concentration of polymer in the organic solvent; the rate of mixing; and to the surfactant employed in the process. Continuous flow mixers can provide the necessary turbulence to ensure small particle size. One type of continuous flow mixing device that can be used to prepare nanoparticles has been described (Hansen et al., J Phys Chem 92, 2189-96, 1988). In other embodiments, ultrasonic devices, flow through homogenizers or supercritical C02 devices may be used to prepare nanoparticles.

1001661 In some embodiments, if suitable nanoparticle homogeneity is not obtained on direct synthesis, then size-exclusion chromatography is used to produce highly uniform drug-containing particles that are freed of other components involved in their fabrication. Size-exclusion chromatography (SEC) techniques, such as gel-filtration chromatography, can be used to separate the particle-bound an NMDA receptor antagonist or other pharmaceutical compound from free the NMDA receptor antagonist, or to select a suitable size range of an NMDA receptor antagonist-containing nanoparticles. Various SEC media, such as Superdex 200, Superose 6, Sephacryl 1000 are commercially available and are employed for the size-based fractionation of such mixtures.

Additionally, in some emebodiments, nanoparticles are purified by centrifugation, membrane filtration and by use of other molecular sieving devices, cross-linked gels/materials and membranes.

Modes of Treatment 1001671 Drugs delivered to the inner ear have been administered systemically via oral, intravenous or intramuscular routes. However, systemic administration for pathologies local to the inner ear increases the likelihood of systemic toxicities and adverse side effects and creates a non-productive distribution of drug in which high levels of drug are found in the serum and correspondingly lower levels are found at the inner ear.

1001681 Provided herein are NMDA receptor antagonist compositions that ameliorate or lessen otic disorders characterized by loss of a plurality of cells (e.g., hair cell, or neurons). Further provided herein are methods comprising the administration of said NMDA receptor antagonist compositions on or near the round window membrane via intratympanic injection. In some embodiments, an auris gel formulations is administered on or near the round window or the crista fenestrae cochleae through entry via a post-auricular incision and surgical manipulation into or near the round window or the crista fenestrae cochleae area. Alternatively, the auris gel formulation is applied via syringe and needle, wherein the needle is inserted through the tynipanic membrane and guided to the area of the round window or crista fenestrae cochleae. The auris gel formulations are then deposited on or near the round window or crista fenestrae cochleae for localized treatment. In other embodiments, the auris gel formulations are applied via microcathethers implanted into the patient, and in yet further embodiments the formulations are administered via a pump device onto or near the round window membrane. In still further embodiments, the auris gel formulations are applied at or near the round window membrane via a microinjection device. In yet other embodiments, the auris gel formulations are applied in the tympanic cavity. In some embodiments, the auris gel formulations are applied on the tympanic membrane. In still other embodiments, the auris gel formulations are applied onto or in the auditory canal.

Intratympanic Injections 1001691 In some embodiments, a surgical microscope is used to visualize the tympanic membrane. In some embodiments, the tympanic membrane is anesthetized by any suitable method (e.g., use of phenol, lidocaine, xylocaine). In some embodiments, the anterior-superior and posterior-inferior quadrants of the tympanic membrane are anesthetized.

1001701 In some embodiments, a puncture is made in the tympanic membrane to vent any gases behind the tympanic membrane. In some embodiments, a puncture is made in the anterior-superior quadrant of the tympanic membrane to vent any gases behind the tympanic membrane. In some embodiments, the puncture is made with a needle (e.g., a 25 gauge needle). In some embodiments, the puncture is made with a laser (e.g., a CO2 laser).

1001711 In some embodiments, a composition disclosed herein is delivered onto the round window membrane. In some embodiments the delivery system comprises a syringe and needle apparatus that is capable of piercing the tympanic membrane and directly accessing the round window membrane or crista fenestrae cochleae of the auris intema. In some embodiments, the syringe has a press-fit (Luer) or twist-on (Luer-lock) fitting. In some embodiments, the syringe is a hypodermic syringe. In another embodiment, the syringe is made of plastic or glass.

In yet another embodiment, the hypodermic syringe is a single use syringe. In a further embodiment, the glass syringe is capable of being sterilized. In yet a further embodiment, the sterilization occurs through an autoclave.

In another embodiment, the syringe comprises a cylindrical syringe body wherein the gel formulation is stored before use. In other embodiments, the syringe comprises a cylindrical syringe body wherein a composition disclosed herein is stored before use. In other embodiments, the syringe contains a buffer, excipient, stabilizer, suspending agent, diluent or a combination thereof to stabilize or otherwise stably store a compound contained therein. In some embodiments, the syringe comprises a cylindrical syringe body wherein the body is compartmentalized in that each compartment is able to store at least one component of a composition disclosed herein. In a further embodiment, the syringe having a compartmentalized body allows for mixing of the components prior to injection into the auris media or auris interna. In other embodiments, the delivery system comprises multiple syringes, each syringe of the multiple syringes contains at least one component of the gel formulation such that each component is pre-mixed prior to injection or is mixed subsequent to injection. In a further embodiment, the syringes disclosed herein comprise at least one reservoir wherein the at least one reservoir comprises a composition disclosed herein. Commercially available injection devices are optionally employed in their simplest form as ready-to-use plastic syringes with a syringe barrel, needle assembly with a needle, plunger with a plunger rod, and holding flange, to perform an intratympanic injection.

1001721 In some embodiments, a needle punctures the posterior-inferior quadrant of the tympanic membrane. In some embodiments, the needle is wider than a 18 gauge needle. In another embodiment, the needle gauge is from 18 gauge to 28 gauge. In a further embodiment, the needle is a 25 gauge needle. Depending upon the thickness or viscosity of a composition disclosed herein, the gauge level of the syringe or hypodermic needle may be varied accordingly.

1001731 In some embodiments, an otoendoscope (e.g., about 1.7 mm in diameter) is used to visualize the round window membrane. In some embodiments, any obstructions to the round window membrane (e.g., a false round window membrane, a fat plug, fibrous tissue) are removed.

1001741 In some embodiments, a composition disclosed herein is injected onto the round window membrane. In some embodiments, 0.4 to 0.5 ccs of a composition disclosed herein is injected onto the round window membrane.

1001751 In some embodiments, the tympanic membrane puncture is left to heal spontaneously. In some embodiments, a paper patch myringoplasty is performed by a trained physician. In some embodiments, a tympanoplasty is performed by a trained physician. In some embodiments, an individual is advised to avoid water.

In some embodiments, a cotton ball soaked in petroleum-jelly is utilized as a barrier to water and other environmental agents.

Other Delivery Routes 1001761 In some embodiments, a composition disclosed herein is administered to the inner ear. In some embodiments, a composition disclosed herein is administered to the inner ear via an incision in the stapes footplate. In some embodiments, a composition disclosed herein is administered to the cochlea via a cochleostomy. In some embodiments, a composition disclosed herein is administered to the vestibular apparatus (e.g., semicircular canals or vestibule).

1001771 In some embodiments, a composition disclosed herein is applied via syringe and needle. In other embodiments, a composition disclosed herein is applied via microcathethers implanted into the patient. In some embodiments, a composition disclosed herein is administered via a pump device. In still further embodiments, a composition disclosed herein is applied via a microinjection device. In some embodiments, a composition disclosed herein is administered via a prosthesis, a cochlear implant, a constant infusion pump, or a wick.

Dosages 1001781 A composition disclosed herein is administered for prophylactic and/or therapeutic treatments. In therapeutic applications, a composition disclosed herein is administered to a patient already suffering from a disorder of the ear characterized by the loss of a plurality of cell, condition or disorder, in an amount sufficient to cure or at least partially arrest the symptoms of the disease, disorder or condition. Amounts effective for this use will depend on the severity and course of the disease, disorder or condition, previous therapy, the patient's health status and response to the drugs, and the judgment of the treating physician.

1001791 The amount of an NMDA receptor antagonist that will correspond to such an amount will vary depending upon factors such as the particular compound, disease condition and its severity, according to the particular circumstances surrounding the case, including, e.g., the specific an NMDA receptor antagonist being administered, the route of administration, the condition being treated, the target area being treated, and the subject or host being treated. In general, however, doses employed for adult human treatment will typically be in the range of 0.02-50mg per administration, preferably 1-15 mg per administration. The desired dose is presented in a single dose or as divided doses administered simultaneously (or over a short period of time) or at appropriate intervals.

Frequency ofAdministration 1001801 In some embodiments, a compositon disclosed herein is administered to an individual in need thereof once. In some embodiments, a compositon disclosed herein is administered to an individual in need thereof more than once. In some embodiments, a first administration of a composition disclosed herein is followed by a second administration of a composition disclosed herein. In some embodiments, a first administration of a composition disclosed herein is followed by a second and third administration of a composition disclosed herein. In some embodiments, a first administration of a composition disclosed herein is followed by a second, third, and fourth administration of a composition disclosed herein. In some embodiments, a first administration of a composition disclosed herein is followed by a second, third, fourth, and fifth administration of a composition disclosed herein.

In some embodiments, a first administration of a composition disclosed herein is followed by a drug holiday.

1001811 The number of times a composition is administered to an individual in need thereof depends on the discretion of a medical professional, the disorder, the severity of the disorder, and the individuals's response to the formulation. In some embodiments, a composition disclosed herein is administered once to an individual in need thereof with a mild acute condition. In some embodiements, a composition disclosed herein is administered more than once to an individual in need thereof with a moderate or severe acute condition. In the case wherein the patient's condition does not improve, upon the doctor's discretion the administration of an NMDA receptor antagonist may be administered chronically, that is, for an extended period of time, including throughout the duration of the patient's life in order to ameliorate or otherwise control or limit the symptoms of the patient's disease or condition.

1001821 In the case wherein the patient's status does improve, upon the doctor's discretion the administration of an NMDA receptor antagonist disclosed herein is given continuously; alternatively, the dose of drug being administered is temporarily reduced or temporarily suspended for a certain length of time (i.e., a "drug holiday").

The length of the drug holiday varies between 2 days and 1 year, including by way of example only, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 10 days, 12 days, 15 days, 20 days, 28 days, 35 days, 50 days, 70 days, 100 days, 120 days, 150 days, 180 days, 200 days, 250 days, 280 days, 300 days, 320 days, 350 days, and 365 days.

The dose reduction during a drug holiday may be from 10%-100%, including by way of example only 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, and 100%.

1001831 Once improvement of the patient's conditions has occurred, a maintenance dose is administered if necessary. Subsequently, the dosage or the frequency of administration, or both, is optionally reduced, as a function of the symptoms, to a level at which the improved disease, disorder or condition is retained. In certain embodiments, patients require intermittent treatment on a long-term basis upon any recurrence of symptoms.

1001841 In some embodiments, the initial administration is a particular an NMDA receptor antagonist and the subsequent administration a different formulation or an NMDA receptor antagonist.

EXAMPLES

Example 1 -Preparation of a Thermoreversible Gel (5)-ketamine 1hgredint Quantity (mg/g of formulation) (S)-ketamine 21.0 methylparaben 2.1 Hypromellose 21.0 Poloxamer 407 378 TRIS HCI buffer (0.1 M) 1677.9 1001851 A 1 0-g batch of gel formulation containing 1.0% of (S)-ketamineis prepared by first suspending Poloxamer 407 (BASF Corp.) in TRIS HCI buffer (0.1 M). The Poloxamer 407 and TRIS are mixed under agitation overnight at 4 °C to ensure complete dissolution of the Poloxamer 407 in the TRIS. The hypromellose, methylparaben and additional TRIS HCI buffer (0.1 M) is added. The composition is stirred until dissolution is observed. A solution of (S)-ketamine is added and the composition is mixed until a homogenous gel is produced.

The mixture is maintained below room temperature until use.

Example 2 -Application of an Enhanced Viscosity (S)-ketamine Formulation onto the Round Window Membrane 1001861 A formulation according to Example 2 is prepared and loaded into 5 ml siliconized glass syringes attached to a 15-gauge luer lock disposable needle. (S)-ketamine is topically applied to the tympanic membrane, and a small incision made to allow visualization into the middle ear cavity. The needle tip is guided into place over the round window membrane, and (S)-ketamine applied directly onto the round-window membrane.

Example 3 -Evaluation of at least one of (S)-ketaminein a Tinnitus Mouse Model 1001871 Twelve Harlan Sprague-Dawley mice weighing 20 to 24 g are used. Each mouse is trained to drink from a water dispenser during periods no sound, but to refrain from drinking in the presence of sound. Each mouse is administered 350 mg of aspirin per kilogram of body weight (mg/kg).

1001881 The control group (n= 10) are administered saline following administration of the aspirin. The experimental group (n= 10) are administered (S)-ketamine (400 mg/kg of body weight) following administration of the aspirin. Administration occurs via an intra-tympanic injection.

1001891 Following administration of (S)-ketaminewhether the mice drink in the absence of external sound is monitored.

Example 4 -Clinical Trial of (S)-ketamine as a Treatment for Tinnitus 1001901 Active Ingredient: (S)-ketamine 1001911 Dosage: 10 ng delivered in 10 pL of a thermoreversible gel. Release of (S)-ketamine is controlled release and occurs over thirty (30) days.

1001921 Route of Administration: Intratympanic injection 1001931 Treatment Duration: 12 weeks 1001941 Methodology * Monocentric * Prosepective * Randomized * Double-blind * Placebo-controlled * Parallel group * Adaptive 1001951 Inclusion Criteria * Male and female subjects between the 18 and 64 years of age.

* Subjects experiencing subjective tinnitus.

* Duration of tinnitus is greater than 3 months.

* No treatment of tinnitus within 4 weeks.

1001961 Evaluation Criteria * Efficacy (Primary) 1. Total score of the Tinnitus Questionnaire * Efficacy (Secondary) 1. Audiometric measurements (mode, frequency, loudness of the tinnitus, pure tone audiogram, speech audiogram) 2. Quality of Life questionnaire * Safety 1. Treatment groups were compared with respect to incidence rates of premature termination, treatment-emergent adverse events, laboratory abnormalities, and ECG abnormalities.

1001971 Study Design 1001981 Subjects are divided into three treatment groups. The first group is the safety sample. The second group is the intent-to-treat (ITT) sample. The third group is the valid for efficacy (VfE) group.

1001991 For each group, one half of subjects to be given diazepam and the remainder to be given placebo.

1002001 Statistical Methods 1002011 The primary efficacy analysis is based on the total score of the Tinnitus Questionnaire in the ITT sample.

The statistical analysis is based on an analysis of covariance (ANCOVA) with baseline as covariant and the last observation carried forward value as dependent variable. Factor is "treatment." The homogeneity of regression slopes is tested. The analysis is repeated for the VfE sample.

1002021 Audiometric measurements (mode, frequency, loudness of the tinnitus, pure tone audiogram, speech audiogram) as well as quality of life are also analyzed via the aforementioned model. The appropriateness of the model is not tested. P values are exploratory and are not adjusted for multiplicity.

1002031 While preferred embodiments of the present invention have been shown and described herein, such embodiments are provided by way of example only. Various alternatives to the embodiments described herein are optionally employed in practicing the inventions. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims (33)

1. CLAIMSWe claim: 1. A pharmaceutical composition for use in the treatment of a disease of the ear characterized by the dysfunction of an NMDA receptor, comprising: (a) an NMDA receptor antagonist in the form of microparticulates; and (b) sterile water, q.s., buffered to provide a perilymph-suitable pH between about 7.0 and about 7.6; and having: (a) less than about 50 colony forming units (cfu) of microbiological agents per gram of composition; and (b) less than about 5 EU/kg composition.
2. 2. The composition of claim 1, wherein the NMDA receptor antagonist is at least one of: an arylcycloalkylamine and a chinazoline.
3. 3. The composition of claim 1, wherein the NMDA receptor antagonist is at least one of: (5)-ketamine, a salt of (s)-ketamine, 7-CK, and a salt of 7-CK.
4. 4. The composition of claim 1, wherein the NMDA receptor antagonist is a fusion peptide comprising (a) a transporter peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins.
5. 5. The composition of claim 1, wherein the NMDA receptor antagonist is released in a therapeutically effective amount from the composition for a period of at least 4 days.
6. 6. The composition of claim 1, wherein the composition is a thermoreversible gel.
7. 7. The composition of claim 1, further comprising a penetration enhancer.
8. 8. The composition of claim 1, further comprising a round window membrane mucoadhesive.
9. 9. The composition of claim 1, wherein the NMDA receptor antagonist is essentially in the form of micronized particles.
10. 10. The composition of claim 1, wherein the practical osmolarity is from about 250 to about 320 mM.
11. 11. A pharmaceutical composition for use in the treatment of a disease of the ear characterized by the dysfunction of an NMDA receptor, comprising: (a) an active agent selected from at least one of (S)-ketamine, salts of (5)-ketamine, 7-CK, salts of 7-CK, and a fusion peptide comprising (a) a transporter peptide and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins in the form of microparticulates; and (b) sterile water, q.s., buffered to provide a perilymph-suitable pH between about 7.0 and about 7.6; and having: (a) less than about 50 colony forming units (cfu) of microbiological agents per gram of composition; and (b) less than about 5 EU/kg composition.
12. 12. The composition of claim 11, wherein the active agent is released from the composition in a therapeutically-effective amount for a period of at least 4 days.
13. 13. The composition of claim 11, wherein the composition is a thermoreversible gel.
14. 14. The composition of claim 11, further comprising a penetration enhancer.
15. 15. The composition of claim 11, further comprising a round window membrane mucoadhesive.
16. 16. The composition of claim 11, wherein the active agent is essentially in the form of micronized particles.
17. 17. The composition of claim 11, wherein the practical osmolarity is from about 250 to about 320 mJVI.
18. 18. A method of treating a disease of the ear characterized by the dysfunction of an NMDA receptor, comprising administering to an individual in need thereof a composition comprising: (a) an NMDA receptor antagonist in the form of microparticulates; and (b) sterile water, q.s., buffered to provide a perilymph-suitable pH between about 7.0 and about 7.6; and having: (a) less than about 50 colony forming units (cfu) of microbiological agents per gram of composition; and (b) less than about 5 EU/kg composition.
19. 19. The method of claim 18, wherein the NMDA receptor antagonist is at least one of: an arylcycloalkylamine and a chinazoline.
20. 20. The method of claim 18, wherein the NMDA receptor antagonist is at least one of: (S)-ketamine, a salt of (s)-ketamine, 7-CK, and a salt of 7-CK.
21. 21. The method of claim 17, wherein the NMDA receptor antagonist is a fusion peptide comprising (a) a transporter peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins.
22. 22. The method of claim 18, wherein the NMDA receptor antagonist is released from the composition in a therapeutically-effective amount for a period of at least 4 days.
23. 23. The method of claim 18, wherein the composition is administered across the round window.
24. 24. The method of claim 18, wherein the NMDA receptor antagonist is essentially in the form of micronized particles.
25. 25. The method of claim 18, wherein the practical osmolarity is from about 250 to about 320 mM.
26. 26. A method of treating a disease of the ear characterized by the dysfunction of an NMDA receptor, comprising administering to an individual in need thereof a composition comprising: (a) an active agent selected from at least one of (S)-ketamine, salts of (S)-ketamine, 7-CK, salts of 7-CK, and a fusion peptide comprising (a) a transporter peptide and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins in the form of microparticulates; and (b) sterile water, q.s., buffered to provide a perilymph-suitable pH between about 7.0 and about 7.6; and having: (a) less than about 50 colony forming units (cfu) of microbiological agents per gram of composition; (b) less than about 5 EU/kg composition.
27. 27. The method of claim 26, wherein the active agent is at least one of: an arylcycloalkylamine and a chinazoline.
28. 28. The method of claim 26, wherein the active agent is at least one of: (S)-ketamine, a salt of (s)-ketamine, 7-CK, and a salt of 7-CK.
29. 29. The method of claim 26, wherein the active agent is a fusion peptide comprising (a) a transporter peptide, and (b) a peptide inhibiting interaction of an NMDA receptor with NMDA receptor interacting proteins.
30. 30. The method of claim 26, wherein the active agent is released from the composition in a therpaeutically-effective amount for a period of at least 4 days.
31. 31. The method of claim 26, wherein the composition is administered across the round window.
32. 32. The method of claim 26, wherein the active agent is essentially in the form of micronized particles.
33. 33. The method of claim 26, wherein the practical osmolarity is from about 250 to about 320 mM.