15.raviteja G V Panner Selvam R Vineeth Chandy

Human Journals
Review Article
April 2022 Vol.:24, Issue:1
© All rights are reserved by Raviteja G V et al.
Extrusion Spheronization and the Recent Advancements in

Pellets
Keywords: Extrusion spheronization, extruder, colon
administer, smedds, meltlets.
ABSTRACT
Raviteja G V1*, Panner Selvam R2, Vineeth Chandy3 Pellets are multi-unit dosage forms, which are frequently
used because they offer manufacturing and therapeutic
benefits over single-unit solid dosage forms. Extrusion
T John College of Pharmacy, Rajiv Gandhi University,
Spheronization is also known as maramuerization. It is a
Gottigere, Bangaluru, Karnartaka,560083 India. multi-step process that produces consistent-sized spherical
particles known as spheres or pellets with diameters
Submitted: 23 March 2022 ranging from 0.5mm to 1.5mm. It is an ideal method
Accepted: 28 March 2022 because it has outstanding product scale-up, narrow
particle size dispersion, flowability, high yield, and excellent
Published: 30 April 2022
process repeatability. The preparation of pellets involves
four steps i.e. granulation, extrusion, spheronization, and
drying. In the extrusion process, different types of extruders
are used namely axial, radial, dome, rotary cylindrical, ram,
etc. The different process parameters used in this technique
are moisture content, temperature, speed, time, load,
friction plate, mixer, etc. The characterization of pellets
www.ijppr.humanjournals.com involves the particle size distribution, density, porosity,
hardness, friability, etc. The surface area is identified by
mean diameter, gas absorption, and air permeability. The
recent approaches in the extrusion spheronization process
are as follows, coating of the pellets/tablets and pellets as
the delivery of the proteins and at last as the fast mouth
dissolving pellets without the use of water.
www.ijppr.humanjournals.com
INTRODUCTION
Advancements in drug delivery systems continue to be prevalent in pharmaceutical and food

research. Macro, micro, and nanoparticulate systems, as well as uniparticulate and
multiparticulate systems, are examples of novel techniques. Nanoparticulate systems, such as
coaxial electrospraying or liposomes, are frequently employed to increase the bioavailability
of solubility of poorly soluble substances. For high doses, Nanosystems can result in a high
weight of the final formulation. Therefore, the improvement of macro and microsystems with
high drug loads is of recent interest. Macro and microparticulate systems can also provide an
enhanced bioavailability and/or site-specific administration into the human gut1.
Because of possible benefits such as predictable gastric emptying, minimal risk of dose
dumping, variable release patterns, and enhanced bioavailability with less inter-and intra-
subject variability, multiparticulate dosage forms are gaining popularity over single unit
dosage forms. One of the most common multi-particulate dose forms is pellets2. Pelletization
is an agglomeration process in which fine powders or granules of bulk pharmaceuticals and
excipients are converted into small, free-flowing, spherical, or semispherical units known as
pellets. The pellets are a convenience for self-administration, compactness, and ease of
manufacture. Pellets are typically in the range of 0.5 and 1.5 mm in size. Pellets as a drug
delivery system provide not only therapeutic benefits, such as reduced gastro-intestinal
irritation and a reduced risk of side effects from dose dumping, but also technological
benefits, such as improved flow properties, a less friable dosage form, narrow particle size
distribution, ease of coating, and uniform packing. Another advantage of using a pellet
formulation is the repeatability of medication blood levels. Pellets are often placed in hard
gelatin capsules, but they can also be compacted into tablets3. Pellets, which are multi-unit
dosage forms, are frequently utilized because they have manufacturing and therapeutic
benefits over single-unit solid dosage forms4. There are various techniques to manufacture
pellets, extrusion spheronization, hot-melt extrusion, solution or suspension layering, powder
layering, high shear pelletization, freeze pelletization, cryopelletization, crystallo-co-
agglomeration, wet spherical agglomeration, spherical crystallization, and much other
pelletization techniques5. Extrusion spheronization is one of the most commonly used
techniques in the formulation of such multiparticulate beads and pellets providing sustained
and controlled release or modified release drug delivery. The extrusion spheronization was
introduced by Reynolds (1970) and by Conine & Hadley (1970) and these will be helpful to
produce uniform size with high drug loading capacity3.
Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

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Extrusion spheronization provides,
• Uniform size, smooth surface, and narrow size which is having good flow properties.
• For masking the bitter taste of API’S.
• Dose dumping can be minimized / avoided6,7.
The following are some of the most current innovative pellet trends:
a. Help to the preparation of modified-release multiple dosage forms with different release
patterns like immediate and sustained release patterns.
b. Available as mouth melt pellets.
c. Polymer-based pellets control the release pattern of the drug.
d. As fast dissolving tablets containing micro pellets.
e. As self-emulsifying pellets.
f. Gastro retentive floating pellets etc.
The patient acceptability of pellets has risen as a result of this tendency. This new trend aids
in providing information about the drug's releasing pattern and bioavailability in the systemic
circulation of the drug, as well as how it has increased patient acceptance of pH-sensitive
drugs releasing the pattern, taste mask, self-emulsification of pellets, and polymer-based
control release of the drugs, mouth melt pellets8.
EXTRUSION SPHERONIZATION
The extrusion spheronization process creates a highly efficient and streamlined development
of the pellets. This extrusion spheronization is mainly used to produce uniform size
spheroids/pellets. The particle size distribution plays a major role which ensures the control
of the variability and helps in improving the flow properties & also during this process there
is less wastage, and the pellets are produced with low friability. Physical properties of the
active pharmaceutical ingredient can be altered easily to produce high bulk density particles,
low hygroscopicity, free dust, and also a smooth surface. This process can incorporate the
higher levels of active components without producing excessively larger particles, two or
more active agents /components with different ratios can be easily combined with the same
units9,10.

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The extrusion-spheronization technology is widely utilized in the pharmaceutical industry

due to its rapid manufacture of pellets of all sizes and shapes along with its low cost, simple
design, and excellent performance11.
Extrusion spheronization mainly involves four steps: -
• Granulation
• Extrusion
• Spheronization
• Drying of pellets
o GRANULATION
The dry powders are mixed to obtain the uniform distribution later on wet granulation or wet
mass is been prepared with good plasticity, by mixing the powder blend and granulating
liquid. The commonly used granulators are planetary mixer or sigma blade mixer and Hobart
mixer12, 13.
o EXTRUSION
The wet granulated mass undergoes the extrusion with the applied pressure to amass until the
flow occurs through the orifice the obtained mass is known as an extrudate.
This process involves the shaping of wet mass into cylindrical rod shapes of uniform
diameter. The extrudate particles at their weight break at an equal weight & also the extrudate
should have enough plasticity12,14.
When rolled during the spheronization process, the extrudate must have enough flexibility to
deform but not so much that the extrudate particles cling to other particles. The granulation
solvent acts as a binding agent for the granules as well as a lubricant for the extrusion
process15.
EXTRUDER
The extruder name itself implies that it is used to develop sufficient pressure to force the
material to flow into uniform openings that produce the extrudate.
In simple words, we can say an extruder is a pump or it is a machine that can produce
pressure14,16.

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The extruder is mainly classified into four categories:
• Screw type extruder
➢ Axial or Endplate extruder
➢ Dome extruder
➢ Radial extruder
• Gravity feed extruder
➢ Rotary cylindrical
➢ Rotary gear
• Sieve and Basket feed extruder
• Piston feed extruder
➢ Ram extruder
Screw type extruder
The screw extrusion has majorly 3 zones, all these zones are having the mechanical principle
of feed zone, transport, comparison zone, and extrusion zone. The screw extruder has one or
two (twin-screw) for feeding the wet mass to an axial or axial extrusion screen.
❖ Axial extruder
The axial extruder is having the die plate which is placed axially, this consists of a feeding
zone, compression zone, and extrusion zone. During the extrusion, the jacketed barrels are
used to control product temperature. The axial extruder screen has been placed at the end of
the screw which is perpendicular to its axis. This extruder is used for making pellets ranging
from 300 microns to a maximum of 1500 micron16,17.
❖ Radial extruder
Radial extruder the screen is been placed perpendicularly on the axis of the screw where the
extrudate is discharging around the screw. In this extruder the transport zone is short and the
materials are been extruded radially around the horizontal axis of the screw which is mounted
through the screens. The pellets range ranges from 400micron to 1500microns.

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❖ Dome extruder
The Dome extruder is similar to the axis extruder, but in this type, the assembly is placed at
the end of the screw by dome shape18.
Gravity feed extruder
Gravity feed extruder consists of both rotary cylindrical and rotary gear extruder where there
is a difference between the design of the two counter-rotating cylinders.
❖ Rotary cylindrical extruder
In the rotary cylindrical type, two cylindrical are present in which one counter-rotating
cylinder is perforated and hallow, and another cylinder is solid and acts as a pressure roller.
❖ Rotary gear cylinder extruder
The rotary gear cylinder is having the counterbored holes with two hallow counter-rotating
gear extruder4,17.
Sieve and Basket feed extruder
Sieve extruders are like flour sifter & the sieve extruder is having a chamber that consists of a
screen or screen and material to be extruded. The damp material passes through the
perforated screen and sieve which forms short and long extrudates with the help of an
oscillating and rotating arm press.
The basket-type extruder is similar to a sieve extruder in which a sieve or screen is a part of a
vertical cylindrical wall, the extrudate is been forced around the vertical holes from the
horizontal plane14.
Piston extruder
This piston extruder is based on the principle of the piston, where the wet mass pushes
through the two screens which are present at the end of the barrel18.
Ram extruder
Ram extruder is the oldest technique of extruder, where a piston displaces & forces the
material to pass through the die at the end. These extruders are mainly used in the

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development phase, where these extruders are used for the formulation purpose as the
rheological properties4.7.
Spheronization
Spheronization is also known as mesmerizer, which consists of a static cylinder and a rotating
friction plate. The spheronizer duration will be around 2-10min and the speed of the friction
plate will be around 200-400 rpm, in this, the optimum spherical pellets are obtained. The
damping of the extruded cylinder occurs in the spinning plate spheronizer known as friction
plate, in which the smaller cylindrical equal length diameter is obtained by breakdown or
extrude. Extrude cylindrically was broken due to interaction of the extrude with a smooth
plate, stationary wall and other extrude particles4,7.
The extrudate formulation determines how pellets are formed during the spheronization
process. Cohesiveness, hardness, and plasticity must all be present in the extruded
granulation. Breaking the cylindrical segments, or extrudate, agglomerating the fractured
segments, and flattening the particles are the three stages of this operation. The extrudate
interacts with the revolving plate, stationary wall, and other extrudate particles, resulting in
the breaking of the cylindrical segments. When the smaller pieces formed during the breaking
stage are scooped up by the bigger granules during the smoothing stage, agglomeration
develops. During the smoothing stage, spherical particles are formed by rotating each granule
around its axis in a variety of planes15.
Drying of pellets
To achieve the desired moisture content drying stage is required. The pellets can be dried at
room temperature and also by elevated temperature by using a fluidized bed drier or try drier.
During the drying of wet mass, the solute gets migrated, which increases the dissolution rate,
pellets with modified surface and this results in less/reduced adhesion4,7.
PROCESS VARIABLES FOR THE EXTRUSION SPHERONIZATION
• Starting material
The starting material which is available in nature influences the hardness, particle size, and
particle shape, this results in a difference in the release rate of the loaded drug. The materials
used in the pellet’s formulation, there is a difference in the quality of pellets of the different
compositions. The pellets which are produced using MCC (microcrystalline cellulose) of

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three different types, there is a difference in the shape and size even it is manufactured in
same conditions of different manfactures19.
• Rheological characteristics
The wet mass of the rheological condition determines the flowability of the extrusion
machine. The presence of optimum rheological conditions leads to good flowability of the
wet mass from the extrude. The variation in the rheological condition makes the extrusion
non-uniform and improper, this leads to the formation of non-uniform pellets9,20,21.
• Moisture content
Moisture content is one of the most critical parameters in the production of pellets from
spheronization. The presence of moisture in the wet mass brings cohesiveness to the powder
this wet mass can be extracted and the spheronizer produces a spherical shape22. For the
preparation of the pellets, the moisture content should be 10-15%. If more amount of water is
present, this leads to agglomeration of pellets spheronization process21. The fine extrudates
are obtained by large variation if the moisture content is less in the dump mass. The
percentage moisture content is obtained by using infra-red moisture content and heated by
using an infra-red lamp23.
• EXTRUSION OPERATIONAL VARIABLES
o Extruders
Axial screw extruder produces the denser material compared to radial screw extruder,
according to Reynolds and Rowe. At the end of the production process, the output is high and
also it shows greater heat production during the process. The quality of the pellet depends on
the screen thickness. The presence of a thinner screen produces rough & loosely bound
extrudate, while the presence of a thicker screen produces smooth and well bound extrude.
This occurs due to higher compaction of wet mass19.
o Extrusion screen/ screen pressure
The stress force is required for the wet mass to pass through small orifice22. The amount of
water added to the granulation purpose is linearly related to screen pressure. The screen
pressure is directly dependent on the amount of load, the amount of water that is used for the
granulation, blend composition, and also a few operational parameters such as pore size and
screw speed, by altering these above parameters leads to slight changes in the screen

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pressure. The orifice screen's properties have an impact on pellet quality; when the orifice
dimension grows, the pellet size grows as well24. But increase in the orifice depth there will
be a decrease in the water content in the extrdate25.
o Extrusion screen hole diameter
The quality of the pellet depends on the extrusion screen which is characterized by two
parameters.
✓ The thickness of the screen
✓ The diameter of the perforations
The presence of dimension on the screen hole during the extrusion plays a major role in the
formulation of the pellet, which affects the final product of the pellet and also the mean
diameter of the pellet. The diameter of the screen hole perforations determines the pellet size,
if we are using larger diameter perforations the larger diameter producing pellets are
produced. With the increase in the extruder size opening, there will be an increase in the
hardness of the tablet from these pellets. The presence of the above two parameters will affect
the pellet formulation such as size, shape, hardness, and surface morphology. The main
selection of the optimal screen size depends on the specific size requirements of pellets and
also based on their application24.
▪ Extrusion extruder type
The extruder type influences the extrudate quality and consequently pellet qualities.
Extruders with screens require the least amount of force. Pellet characteristics will vary
depending on the type of extruder used. The extruder selection is very critical because it is
not interchangeable. All the extruders are not designed for pharmaceutical use and some are
used for food-grade extruders in which it doesn’t meet the GMP (Good Manufacturing
Practices) requirements. In some cases, only water content is required when there is a change
in extruder type24.
▪ Extrusion speed
The output of the extrusion and final pellet quality depends on the extruder speed. An
increase in the extrusion speed results in an increase in the compressed force of the extruder
present in the wet mass. The increase in the speed causes surface impairment, roughness &
shark skinning these lead to lower the quality of the pellets, because during the

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spheronization process the extrude will break unevenly during the initial stages26. The surface
impairment leads to the production of wider size distribution, lower the pellet quality and also
the generation of fines occurs by the uneven breakage in the extrude19.
▪ Extrusion temperature
The temperature control is important in extrusion spheronization during the formulation of

the thermolabile drug and also to optimize moisture content. During the extrusion cycle, there
is a rise in the temperature, which causes the granulating liquid to evaporate from the
granules this leads to a difference in the quality of extrudate batches. To avoid the rise in
temperature in the extrusion cycle the colling jackets are used around the barrel of the screw
extruder to keep the temperature at the predetermined limits during the formulation
process19,27.
• Spheronization operational variables
▪ Spheronizer load
The pellets yield decreases at a specific range with an increase in the spheronization speed
with less spheronization load. But there is an increase in the pellet yield that occurs with an
increase in the spheronization time at the higher spheronization load. With the increase in the
spheronizer load, there will be an increase in the mean diameter. Newton et al. reported that
at low load it gives poor molecular interaction but using high load poor plate and molecular
interaction, they studied that at low load i.e., they used 50 & 100g of load which produces
pellets of best length and it is having a minimum thickness and the circular structural is least.
But while using the higher load like 750 & 1000g these produce round granule in long run,
these procedure takes more time12,27.
▪ Spheronizer speed
Spheronizer speed plays a major role in the quality of the spheres. At very low speed no
changes of the shape occur in the extrudate and at high-speed size reduction of the particles
occurs. The spheronizer speed affects the hardness, size, shape\sphericity, flowrate, friability,
porosity, and density of the pellets. The spheronizer speed should be around 1000 to 2000
rpm for better quality according to Wan et al12. The lower spheronizer speed leads to the low
harsh environment in the extrudate but during the high spheronization speed there is an
increase in the sphericity along with high residence time, and it enhances the densification of

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the pellets according to Ronowicz et.al. The optimized spheronization speed is required to
achieve spherical pellets with a narrow size distribution27.
▪ Spheronizer time
The influence of spheronization duration during high spheronization speed is extremely

small, but a lower spheronization speed in an appropriate environment will result in an
increase in total pellet yield. However, at low spheronizer speeds, the extrudate allows wet
particles to agglomerate fine particles, resulting in a reduction in fine particles in the
spheronizer. According to Wan et al., spheronizer time will be around 5-15min range to
obtain the good quality. These spheronizer times had a variety of effects during the
formulation particle size distribution, higher sphericity, density, and also changes in the yield
occurs these the changes occurred by altering the spheronization time. The residence time is
the major factor to obtain the superior product, however, the yield in the targeted zone will
get lowered by an increase in the spheronization time. According to Ronowicz et al.,
spheronization speed and residence are the two important factors in producing good quality
pellets26, 27.
• Mixer
Bryan et al. made a comparison between the screw mixer and planetary-based mixer process
in extrusion spheronization were reported. The pellets which were formulated using the screw
mixer showed better/higher yield, strength, and these forms narrow size distribution of small
pellets has compared to the planetary mixer.
There are different types of granulators that are used for mixing the powders with the help of
the granulating liquid. The planetary mixer, sigma, or high sear mixer are the most commonly
used granulators12,27.
• Friction plate
In the spheronization process, a friction plate plays an important role, it consists of a grooved
surface, and the frictional force increases during the spheronization process. In the case of
obtaining good quality pellets, the friction plate and the diameter of the friction plate plays an
important parameter.

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There are two types of geometry grooves
➢ Crosshatch grooves
➢ Radial grooves geometry27
Michie et al. has been investigated the effect of different designs plates of the spheronizer,
there are mainly three effects which include radial, crosshatch & striated edge design. All of
these will show the effect on the physical properties of the pellet formulation. The change in
the plate design will affect the yield value and also the marginal effect of the pellet was
observed28.
Zhang et al. investigated the effect of plate surface protuberances on the pellet water content
pellet size, shape, and yield of the pellets.
The experimental results showed pyramidal design gave satisfactory performance among all
four criteria, that is pattern plates large studs, saw-toothed, pyramidal, and small studs29.
CHARACTERIZATION OF EXTRUSION SPHERONIZATION
• Particle size distribution
The pellets sizing plays a significant role in the influence of kinetics release. The parameters
which influence the size of the pellet are geometric mean diameter, mean ferret diameter,
particle size distribution, and the width and length of the pellet size can be determined. Sieve
analysis is the method that is widely used in measuring the particle size distribution by using
the sieve shaker and also by using microscopy the particle size distribution can be determined
directly. To check the diameter of the pellets scanning electron microscope (SEM) and
optical microscopy are used30.
• Surface area
The surface area controls the characteristics of pellets which includes the pellet's size, shape,
porosity, and surface roughness.
There are three methods of measuring the surface area of pellets.
▪ Mean diameter
▪ Gas absorption
▪ Air permeability

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❖ Air permeability
The air permeability techniques are commonly employed in the pharmaceutical industry for
specialized surface measurements, particularly where batch-to-batch fluctuations must be
controlled. Fisher sub-sieve sizer is a commercially available device. The surface area of a
substance acts as the primary barrier to the passage of a fluid, such as air, through a plug of
compacted material. The specific surface area of uncoated drug granules was estimated in this
study using sieve analysis data30.
❖ Mean diameter
The mean diameter doesn’t useful / does not provide many contributions for arising
morphological characteristics such as surface roughness, porosity, and also the pellet shape25.
❖ Gas absorption
The gas absorption is commonly known as the BET method which was developed by
Brunauer, Emmet, and Teller (1937). This method was carried out by placing the sample in
the chamber and air was evacuated within it. In this method the volume of nitrogen is used
which is absorbed by the substrate in the evacuated glass blub and it is measured at different
pressures19,25.
• Porosity
The capillary action of the dissolved medication is affected by the porosity of pellets, which
determines the rate of drug release from the pellets. Scanning electron microscopy (SEM) and
a mercury porosimeter can both be used to determine the porosity of the pellets. Optical
microscopy and scanning electron microscopy, together with image processing, can be used
to assess the porosity of pellets in a quantitative way25.
• Density
Changes in the formulation and/or method can modify the density of pellets, which can have
an impact on other processes or factors such as capsule filling, coating, and mixing. The bulk
density of the pellets is measured using an automated tapping machine. True density is a term
that describes the degree to which a substance is compacted or densified25,30.

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• Hardness and friability
During the handling, shipping, storage, and also other operational units result in producing
dust, so these hardness and friability play a role in producing the pellets. The different
variables in the variables as well as the different variations in the formulation process of
pellets result in potentially significant variations in the hardness and friability of the pellets.
The instrument which is used to check the hardness value is the Kaul pellet hardness tester.
The instrument used to determine the friability is an Erkewa-type tablet friabilator and to
generate the abrasion Turbula mixer is used for a fixed period which is combined with glass
beads of a certain diameter. The other method to determine the friability is a fluidized bed
with the Wurster insert, in which the steam of air is used19,25.
• Tensile strength
The tensile strength of the pellet is determined by the tensile apparatus which is having 5 kg
load cell, the pellets are strained until the failure occurs. The tensile strength is calculated and
load is recorded by applying the value for failure load & by using the pellets radius30.
RECENT ADVANCEMENTS IN PELLETS
TARGET SPECIFIC PELLETS
Pellets are of particular relevance for use as cores in the manufacture of coated oral delivery
systems due to their spherical or pseudo-spherical shape, consistent size, and smooth surface.
Pellet formulations for colon administration can be coated with enzymatically degradable,
pH-sensitive, or time-controlled polymer coatings. While layers susceptible to microbial
breakdown or pH-dependent dissolution allow for targeted release based on physiological
characteristics of the environment in which the drug is to be delivered. Time-based coats
have the inherent ability to delay release throughout the small intestinal transit of the dosage
form, regardless of regional differences in pH, microbial population, and other variables.
Colon delivery methods based on coated pellets have been developed to take advantage of
physiological pH fluctuations in the small and large intestine, to be enzymatically degraded
by the colonic microbiota, or to delay the onset of release dependent on the time it takes for
dose forms to reach the colon31.

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FLOATING PELLETS
The possession of Gastro retentive floating pellets is to extend the residence duration of the
medicine and release it in a regulated manner. Because the floating pellets have a low bulk
density, they float for a longer time in the stomach environment, increasing the drug's
bioavailability32.
SELF EMULSIFYING PELLETS
The solid self-emulsifying pellets of nitrendipine(SE NTD), a weakly water-soluble

medication, were found and analyzed by Zhiyuan Wang. The recent findings suggest that SE
NTD pellets with a 30% liquid self-emulsifying drug delivery system (SEDDS) may be
efficiently produced utilizing the extrusion/spheronization method. The SE pellets that were
produced were uniform in size, spherical in shape, and hard enough. The self-emulsifying
properties of pellets were found to be intact. After self-emulsification in water, the droplet
size distribution of the SE pellets was nearly equal to that of the liquid SEDDS, and in vitro
dissolving performance was comparable for the liquid SEDDS and SE pellets, both of which
were significantly larger than conventional tablets. When compared to liquid SEDDS, the
oral bioavailability of NTD from SE pellets was much greater than that of conventional
tablets, with no apparent difference. As a consequence, the extrusion spheronization
technique may be utilized to generate solid SE pellets from liquid SEDDS, which can aid the
oral absorption of poorly soluble medicines such as NTD33.
COATING OF PELLETS
The development of better coating processes has been a major focus of recent advancements
in pellet technology. Because the characteristics of the polymer coating, including the
thickness of the polymeric film, can affect the release pattern of a pharmaceutical product,
new approaches are being developed that give greater flexibility and stability. One of these
processes is Wurster fluidization, a bottom-spraying technology known for its accurate film
coating capabilities. The spray nozzle is centered on the coating zone and is positioned at the
bottom of the product container. The impact and acceleration forces that occur during this
process cause agglomerates to develop, which are subsequently smoothed out into
homogenous and dense pellets before being dried. Despite the benefits of merging the several
phases of pelletization into a single processing unit, which reduces processing time and

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material handling, this approach is still not commonly used in the industry due to
considerations such as cost and equipment availability10.
PELLETS AS PROTEINS
Protein-based therapeutics such as vaccines, antigens, and hormones have become more
popular, but limitations in biology limit the development and production of protein
pharmaceuticals. Various tactics of drug delivery have been explored, including, different
sizes, compositions, and shapes. The rapidly expanding pharmaceutical business is constantly
looking for new active compounds to produce, which necessitates the development of an
appropriate dosage form capable of properly delivering those molecules in the body. The use
of pellets as a means for drug delivery offers biopharmaceutical advantages and overcomes
the limitations of therapeutic proteins. Most commonly and effectively, extrusion
spheronization can be used to produce multiparticle delivery systems for the oral
administration of therapeutic enzymes and other proteins of interest with high-retained
activity. Industrial use of therapeutic proteins and enzymes has increased, and these
macromolecules are replacing low molecular weight chemicals due to their potency and
specificity. As pharmaceutical industries develop new oral formulations and delivery
technologies, they will continue to focus on these molecules in the future34.
MELT IN MOUTH PELLETS
Extrusion-spheronization is a common method for producing dense granules with regulated

and high sphericity in pharmaceutical and other industries. It is a multistep procedure
incorporating several variables that have an impact on the final qualities of the pellets
produced. The creation of "Melt in mouth pellets," or Meltlets®, is a revolutionary expansion
of pellets as a delivery technique. Meltlets® are delightfully scented, rapid dissolving
medication or nutraceutical pellets packaged in single-serve sachets. The contents of the
sachet should be poured immediately into the mouth, where they will break down into a soft
mass that may be taken without water. These mouth-dissolving pellets can include a wide
range of medications and nutraceuticals, resulting in improved patient compliance and a
competitive advantage in therapeutic categories where similar products are available.
Ketkeedeshmukh et al. worked on the antioxidant activity of Meltlets of Soy Isoflavones
showing that there is no change/alteration in the process parameter of the extrusion
spheronization35.

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DEM MODEL IN PELLETS
Various interfering factors, including plastic deformation, breaking, attrition, and

coalescence, influence the rounding of wet cylindrical extrudates in the spheronizer after the
extrusion step. The particle rounding process in the spheronizer is not adequately described
due to the complexity of these mechanisms, which are dependent on particle dynamics. To
describe how the particle shape changes due to collisions, the Discrete Element Method
(DEM) on the microscale is combined with a Particle Shape Evolution (PSE) model on the
macro scale in this study. A new contact model was built for the DEM simulation to represent
the cyclic, dominating viscoplastic deformation behavior. A precise contact model in the
DEM is required in order to acquire correct deformation data for use in the PSE model. As a
result, a single-particle elastic-plastic contact model was used36.
SUGAR PELLETS
DSP (dexlansoprazole) is a proton pump inhibitor that degrades at an acidic stomach pH and
is used to treat gastro-oesophageal reflux disease (GERD). Enteric coating slows the release
of the drug in the stomach & makes it more effective. The inert core material was a sugar
pellet that was exposed to drug loading, barrier coating, immediate delayed-release, and
prolonged delayed-release coating. For drug retardation, L-HPC-31(low substituted
hydroxypropyl cellulose) 5%was used37. The study was made on a multiparticulate drug
delivery system loaded with galantamine hydrobromide in the drug was applied to the sugar
pellets using a medium HPMC(hydroxypropyl methylcellulose suspension)a study was to
refine the layering process to influence the critical process parameters in the formation of
agglomerates. These five factors showed a critical impact on the degree of agglomeration of
pellets i.e., product temperature, spray rate, spray pressure, airflow, HPMC concentration
using factorial design. It was found that there is the highest agglomeration when the first
factor was at a high level and the second factor was at a high level38.
CONCLUSION: -
The aim of this study is to outline the numerous elements of the extrusion spheronization
process that affect pellet quality. Process parameters, equipment parameters, and formulation
parameters in the extrusion–spheronization method should all be thoroughly explored
because they have the greatest impact on the final pellet properties. The hardness, porosity,
surface morphology, and sphericity of the pellets are influenced by process parameters such

221
as drying rate, extrusion–spheronization speed, and time. Equipment parameters, on the other
hand, have an impact on pellet yields, size distribution, and strength characteristics. Surface
morphology, density, structural, and mechanical properties of pellets are all affected by
formulation parameters such as moisture content and friction plate, etc. Pelletization has
taken a unique place in the pharmaceutical business, particularly in the creation of
multiparticulate oral controlled release dosage forms, because of its simple design, great
efficiency in creating spherical pellets, and quick processing.
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Human Journals

Extrusion Spheronization and the Recent Advancements in

Advancements in drug delivery systems continue to be prevalent in pharmaceutical and food

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

Extrusion spheronization provides,

• For masking the bitter taste of API’S.

• Dose dumping can be minimized / avoided6,7.

b. Available as mouth melt pellets.

c. Polymer-based pellets control the release pattern of the drug.

d. As fast dissolving tablets containing micro pellets.

f. Gastro retentive floating pellets etc.

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

The extrusion-spheronization technology is widely utilized in the pharmaceutical industry

Extrusion spheronization mainly involves four steps: -

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

The extruder is mainly classified into four categories:

• Screw type extruder

➢ Axial or Endplate extruder

• Gravity feed extruder

• Sieve and Basket feed extruder

• Piston feed extruder

Screw type extruder

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

Gravity feed extruder

❖ Rotary cylindrical extruder

❖ Rotary gear cylinder extruder

Sieve and Basket feed extruder

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

PROCESS VARIABLES FOR THE EXTRUSION SPHERONIZATION

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

• EXTRUSION OPERATIONAL VARIABLES

o Extrusion screen/ screen pressure

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

o Extrusion screen hole diameter

✓ The thickness of the screen

✓ The diameter of the perforations

▪ Extrusion extruder type

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

The temperature control is important in extrusion spheronization during the formulation of

• Spheronization operational variables

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

The influence of spheronization duration during high spheronization speed is extremely

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

There are two types of geometry grooves

➢ Radial grooves geometry27

CHARACTERIZATION OF EXTRUSION SPHERONIZATION

• Particle size distribution

There are three methods of measuring the surface area of pellets.

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

• Hardness and friability

RECENT ADVANCEMENTS IN PELLETS

TARGET SPECIFIC PELLETS

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

SELF EMULSIFYING PELLETS

The solid self-emulsifying pellets of nitrendipine(SE NTD), a weakly water-soluble

Citation: Raviteja G V et al. Ijppr.Human, 2022; Vol. 24 (1): 205-223.

MELT IN MOUTH PELLETS

Extrusion-spheronization is a common method for producing dense granules with regulated