Pharmacology

-It is the study of the biological effects of chemicals or drugs.

Definitions

Pharmacopeias:

- are the total of all authorized drugs available within the country.

Medication:

-is a substance administered for diagnosis, cure, treatment, mitigation or prevention.

Prescription:

-the written direction for the preparation and the administration of the drug.

The therapeutic effect:

-is the primary effect intended that is the reason the drug is prescribed such as morphine sulfate is
analgesia.

Side effect:

-secondary effect of the drug is one that unintended, side effects are usually predictable and may be
either harmless.

Drug toxicity:

-deleterious effect of the drug on an organism or tissue, result from overdose or external use.

Drug allergy:

-is immunological reaction to a drug.

Drug interaction:

-occur when administration of one drug before or after alter effect of one or both drug.

Drug misuse:

-Is the improper use of common medications in way that lead to acute and chronic toxicity for example
laxative, antacid and vitamins.

Drug abuse:

-is an inappropriate intake of substance either continually or periodically.

Drug dependence:

-is a persons reliance on or need to take drug or substance there are two type of dependence:
Physiological dependence:

-is due to biochemical changes in the body tissue these tissue come to require substance for normal
function.

Psychological dependence:

-is emotional reliance on a drug to maintain a since of wellbeing accompanied feeling of need.

Drug habituation:

-denotes a mild form of psychological dependence.

Illicit drug:

-also called street drug are those sold illegally.

Drug Names

Chemical name

- Describes the drug’s chemical composition and molecular structure

ex:

(+/-)-2-(p-isobutylphenyl) propionic acid

Generic name (nonproprietary name)

- Name given by the United States Adopted Name Council

Ex: ibuprofen

Trade name (proprietary name)

- The drug has a registered trademark; use of the name restricted by the drug’s patent owner (usually
the manufacturer)

ex: Motrin®, Advil®

Drug

-It is any chemical that affects the physiologic processes of living organisms.

-natural product, or pharmaceutical preparation intended for administration to a human to diagnose or

treat a disease,

Sources of drugs

1. Plant or plant parts - which has been used since prehistoric times

2. Animal products – like insulin, growth hormones, thyroid drugs

3. Inorganic compounds – Aluminum, flouride, iron

4. Synthetic sources – scientist used genetic engineering to alter bacteria to produce chemicals
that are therapeutic and effective like vaccines.

Different forms of drug

1. Tablets and capsules

• Enteric-coated

• Sustained or extended release

• Lozenges

2. Solutions and suspensions

• Syrup

• Elixirs

• Sterile solutions and suspension

3. Skin patches

4. Aerosols

- Nasal sprays

5. Ointments, creams, lotions

6. Suppositories

• Vaginal

• Urethral

• Rectal

Routes of Administration

a. Enteral Administration

 Sublingual- placed under the tongue

Buccal – placed between the cheek and the gum

 Oral – per orem

Rectal

» Parenteral Administration

• Intravenous

Intramuscular
• Subcutaneous 20

Intrathecal

- injection of the drug through the theca of the spinal cord and into the subarachnoid space

• Intra-articular – drugs used to treat arthritis

• Transdermal – application of drugs to the skin for absorption into the circulation

• Topical- application of drugs to the surface of the body to produced localized effect

- used to treat disorders of the skin, eyes, nose, mouth, throat, rectum, and vagina

Inhalation- drugs used to treat asthma or rhinitis, whereas a systemic effect is observed when a
general anesthetic(e.g halothane) is inhaled.

PHARMACODYNAMIC

Pharmacodynamics

- Study of the mechanism of drug actions in living tissue

- What a drug does to the body- relates to the site of drug action

- The site of drug action is the specific cell, tissue, or organ where the drug works

3 Principles about Drug Action

1. Drugs do not create new function or response but modify or alter existing physiologic activity
within the body;

2. Drugs interact with the body in several different ways. No drug has a single action

3. Drug effects are determined by the drug’s interaction with the body.

Pharmacodynamics

Drugs -induced alterations to normal physiologic function

Positive change - Therapeutic effect - Goal of therapy

Mechanism of Action

- Ways in which a drug can produce a therapeutic effect

• The effects that a particular drug has depends on the cells or organ targeted by the drug.

• Once the drug hits its “site of action” it can modify the rate at which a cell or tissue functions.
Mechanism of Action

1. Receptor Interaction

2. Enzyme Interaction

3. Non-Specific Interaction

1. Receptor Interaction

- Drug structure is essential

- Involves the selective joining of drug molecule with a reactive site on the cell surface that elicits
a biological effect
- Receptor is the reactive site on a cell or tissue
- Once the substance binds to and interacts with the receptor, a pharmacologic response is
produced

Affinity- used to describe the strength of the drug’s binding to receptors

The drug with the best “fit” or affinity will elicit the best response

Drug Action

Interaction between the drug and molecular, cellular components (mechanism of action)

Drug Action may be:

Agonist –Drug binds to receptor-there is a response.

(Adrenergic Agents) Fig. 2.7 B

Antagonist-drug binds to receptor-no response-prevents binding of agonists

(Alpha & Beta Blockers) Fig. 2.7 C

Competitive Antagonist- act with receptor sites to block normal stimulation producing no effect

Noncompetitive Antagonist – prevent reaction of another chemical with different receptor site on that
cell

Parameters of Drug Action

Onset of Action- interval between time drug is administered & first sign of its effect.

Duration of Action- length of time the drug exerts pharmacologic effect.

Peak Action – drug reaches its highest blood/plasma concentration

2. Enzyme Interaction

- Enzymes- are substances that catalyze nearly every biochemical reaction in a cell.
 - Drugs can interact with enzyme systems to alter a response
- Inhibits action of enzymes-enzyme is “fooled” into binding to drug instead of target cell
- Protects target cell from enzyme’s action (ACE Inhibitors)

3. Non-Specific Interaction

- Not involving a receptor site or alteration in enzyme function

- Main site of action is cell membrane or cellular process
- Drugs will physically interfere or chemically alter cell process
- Final product is altered causing defect or cell death
- Cancer drugs, Antibiotics

Half - Life

• A measure of the time required for elimination.

-Is determined by an individual’s ability to metabolize and excrete a particular drug

- When the half-life of the drug is known, dosages and frequency of administration can be calculated.

For example: if a patient is given 100 mg of a drug that has a half-life of 12 hours, it will show like this:

Time (Hours) Half-life Drug remaining in body ( %)

0 --- 100 mg (100 )

12 1 50 mg (50)

24 2 25 mg ( 25)

36 3 12.5 mg. (12.5)

48 4 6.25 mg ( 6.25)

60 5 3.12 mg ( 3.12)

The nurse is giving a medication that has a high first-pass effect. The physician has changed the route
from IV to PO. The nurse expects the oral dose to be:

1. Higher because of the first-pass effect.

2. Lower because of the first-pass effect.

3. The same as the IV dose.

4. Unchanged.
Areas of Pharmacology

Pharmaceutics Pharmacokinetics Pharmacodynamics

Pharmaceutics

- The study of how various drug forms influence pharmacokinetic and pharmacodynamic
activities.

Pharmacokinetics

- The study of what the body does to the drug molecules.

Pharmacodynamics

- The study of what the drug does to the body.

- the mechanism of drug actions in living tissues

Pharmacotherapeutics

- The use of drugs and the clinical indications for drugs to prevent and treat diseases.

Pharmacognosy

- The study of natural (plant and animal) drug sources.

- formerly called materia medica (medicinal materials) and is concerned with botanical or zoologic
origin.

Dose of formulated drug

Dose of formulated drug

Admi
nistra
tion
Disintegration
• Pharmaceutical Phase
Dissolution

Drug available for absorption

Absorption
Distribution
• Pharmacokinetic Phase Metabolism
Excretion

Drug available for action

• Pharmacodynamic Phase Drug receptor-Interaction

Phases of Drug activity EFFECT

Pharmacokinetics
Phase

Absorption

- A drug to produce a pharmacologic effect, it must be absorbed or transported from its site of
administration (GI tract, muscle, skin) into the bloodstream
- The rate at which drugs are absorbed determines the onset of effect.
- In turn, the amount of drug absorbed determines the intensity of effects
- Both drug-related & patient-related factors influence drug absorption
First pass effect

The metabolism of a drug and its passage from the liver into the circulation

– A drug given via the oral route may be extensively metabolized by the liver before reaching the
systemic circulation (high first-pass effect)

– The same drug—given IV—bypasses the liver, preventing the first-pass effect from taking place,
and more drug reaches the circulation

Factors that affect the absorption of the medication in the stomach:

– Acidity of the stomach

– The presence or absence of food or fluid

– Age of the patient

– Presence of other types of medication

Absorption

- Drugs administered sublingually or in buccal mucosa, they are absorbed in the highly
vascularized (large blood supply) tissue like under the tongue.
- Bypassed the liver
- Absorbed rapidly in the bloodstream and delivered at the site of action

• Parenteral

- Is the general term meaning any route other than the stomach, most commonly it refers to
injection like subcutaneous, intradermal and intramuscular
- Advantage of bypassing the first pass effect
- Absorbed at the site of injection
- Intravenous
• Delivers drug directly into the bloodstream
• Fastest absorption
- Topical drugs
• Absorbed locally and effect is non-systemic
- Inhaled drugs will be transported and absorbed in the air sacs or alveoli

Distribution

- It refers to the transportation of drug via the bloodstream to its site of action.
- For a drug to achieve its therapeutic effect, it must proceed to the part of the body or tissue
with which it will react.
- At this point some drugs are eliminated in the liver and kidney

Metabolism

- Biotransformation in the liver

 - It involves biochemical alteration of the drug to inactive metabolite, a more soluble compound
or to a more potent active metabolite
- Other metabolic tissue: skeletal muscle, kidney, lungs, intestinal mucosa
- Delayed drug metabolism results in:
• Accumulation of drugs
• Prolonged action of the drugs
- Stimulating drug metabolism causes:
• Diminished pharmacologic effects

Excretion

- Elimination of drug in the body

- Whether active or inactive, drugs must eventually be removed from the body
- Kidney ( main organ)
- Other organ of excretion: the bowel and liver
- Other routes of excretion: through sweat and saliva

International Drug Standards Regulations

Federal control for the protection of consumers who used drugs did not exist until the beginning of the
twentieth century. After a number of catastrophic incidents in which death resulted from the use of
adulterated drugs, the first federal statute controlling the manufacture of drugs was passed - the Food
and Drug Act of 1906. It required that all drugs marketed in the United States meet minimal standards
of strength, purity and quality.
The act also established the U.S. Pharmacopoeia (USP) and the National Formulatory( NF) as the
official legal standards for drugs in the United States. Federal Food, Drug and Cosmetic Act of 1938
added the requirement that a drug be shown to be safe before it could be distributed in interstate
commerce.

An amendment to this act known as the Durham- Humphrey Amendment, was enacted in 1952.
It required that certain drugs be classified as legend drugs and that they be labelled with the legend
" Caution- Federal law prohibits dispensing without prescription." It also specified that all other drugs
approved for use be considered nonprescription drugs. These could be sold directly to the consumer
without the need for a prescription.

In 1962, this act was again amended by the Kefauver- Harris Amendment. It added the
requirement that both prescription and nonprescription drugs be shown to be effective as well as safe.

This was followed in 1970 by the Comprehensive Drug Abuse Prevention and Control Act also known as
the Controlled substance Act of 1970 which further classified drugs according to their potential for
physical or psychological dependence and abuse. It also regulated the manufacture and distribution of
drugs considered capable of causing dependence.
As a result of these federal statutes, all drugs may be classified into Four Categories:
1. Prescription or legend drugs
2. Nonprescription or over the counter ( OTC) drugs
3. Investigational drugs
4. Illicit or street drugs

SAFETY DURING PREGNANCY (PREGNANCY CATEGORIES)

FDA PREGNANCY CATEGORIES

Category A

Adequate studies in pregnant women have not demonstrated a risk to the fetus in the first trimester of
pregnancy, there is no evidence of risk in later trimesters

Category B

Animal studies have not demonstrated a risk to the fetus but there are no adequate studies in pregnant
women or animal studies

Category C

Animal studies have shown an adverse effect on the fetus but there are no adequate studies in humans;
the benefits from the use of the drug in pregnant women may be acceptable despite its potential risk

Category D

There is evidence of human fetal risk, but the potential benefits from the use of the drug in pregnant
women may be acceptable despite its potential risk

Category X

Studies in animals or humans demonstrate fetal abnormalities or adverse reaction; reports indicate
evidence of fetal risk

The Controlled Substances Act of 1970 regulates the manufacturing, distribution and dispensing of
drugs that are known to have abuse potential.

• Schedule I (C-I)

• Schedule II (C-II)

• Schedule III (C-III)

• Schedule IV(C-IV)

• Schedule V (C-V)
Schedule I

- Drugs in Schedule I have a high potential for abuse and no accepted medical use in the United
States

Eg. Heroin, LSD, Ecstasy

Schedule II

- Drugs in Schedule II also have a high potential for abuse, but do have a currently accepted
medical use in the United States. It has been determined that abuse of a drug included in this
schedule may lead to a severe psychological or physical dependence.

Eg. Meperidine, morphine, cocaine, oxycodone

Schedule III

- Schedule III drugs have accepted medical uses in the united States, but they have a lower
potential for abuse than drugs in Schedules I and II.

Eg. Acetaminophen with codeine, hydrocodone

Schedule IV

- Schedule IV drugs have a low potential for abuse relative to Schedule III drugs. Abuse of
Schedule IV drugs may lead to limited physical or psychological dependence as compared with
Schedule III drugs.

Eg. Librium, Valium

Schedule V

- Schedule V drugs have the lowest abuse potential of the controlled substances. They consist of
preparations containing limited quantities of certain narcotic drugs generally used for
antitussive and antidiarrheal properties.

Eg. Lomotil, Robitussin

STAGES OF DRUG DEVELOPMENT

1. Pre-Clinical Trials

- Chemicals that may have therapeutic value are tested on laboratory animals for two main
purposes:

a) To determine whether they have the presumed effects in living tissue

b) To evaluate any adverse effects

• Animal testing is important because unique biological differences can cause very different
reactions to the chemical.
• At the end of the preclinical trials, some chemicals are discarded for the ff reasons:

a) Chemicals lacks therapeutic activity when used with living animals

b) Chemicals is too toxic
c) Chemicals are highly teratogenic

2. Phase I Studies

- Uses human volunteers to test the drugs

- These studies are more tightly controlled than preclinical trials and are performed by specially
trained clinical investigators
- The volunteers are fully informed of possible risks and may be paid for their participation.
- Usually the volunteers are healthy, young men

•Investigators in Phase I studies scrutinize the drugs being tested for effects in humans

•Many chemicals are dropped for the ff reasons

A. They lack therapeutic effect in humans

B. They cause unacceptable adverse effects
C. They are highly teratogenic
D. They are too toxic

�Some chemicals move to the next stage of testing despite undesirable effects.

�Like the hypertensive drug :Minoxidil (Loniten) was found to effectively treat malignant hypertension
but it caused unusual hair growth on the palms and other body areas

3. Phase II Studies

- Allows clinical investigators to try out the drug in patients who have the disease that the drug is
designed to treat.
- Patients are told about the possible benefits of the drug and are invited to participate in the
study
- Various sites across the country

• May be removed from further investigation for the following reasons:

a. It is less effective than anticipated

b. It is too toxic when used with patients
c. It produces unacceptable adverse effects
d. Has low benefit to risk ration – therapeutic benefit it provides does not outweigh the risk of
potential

4. Phase III Studies

- Involves use of the drug in a vast clinical market

- Prescribers are informed of all the known reactions to the drug and precautions required for its
safe use.
- Patients will be observe very closely and monitored
- Asked to make journals and record any symptoms they experience
�Drugs that finish Phase III studies are evaluated by the FDA, which relies on committees of experts
familiar with the specialty area in which drugs will be used.

�Only those drugs that receive FDA committee approval may be marketed.

5. Phase IV studies

- After a drug is approved for marketing, it enters a phase of continual evaluation.

- Prescribers are obligated to report to the FDA any untoward or unexpected adverse effects
associated with drugs

INDIVIDUAL VARIATION OF PHARMACOLOGICAL RESPONSE

While an understanding of the fundamental scientific principles discussed this far is essential in
understanding how drugs exert their effects, it should be noted that considerable variations may occur
in the response of any two individuals to the same drug and dosage regimen.

THE FOLLOWING ARE SOME OF THE FACTORS THAT HAVE BEEN SHOWN TO CONTRIBUTE TO
INDIVIDUAL VARIATION OF DRUG RESPONSE

AGE

- those clients who are at age extremes, the very young and very old, often exhibit great variations in
drug absorption, distribution, bio transformation and elimination.

GENDER

-male and female individuals have different body compositions.

-The proportion of fat to lean body mass may influence the action as well as the distribution of drugs
through the body.

BODY WEIGHT

- increased body weight may necessitate the use of higher drug doses because the dose required to
reach equivalent levels of a drug in body tissues.

DISEASE STATES

- underlying disease states may affect an individual's response to a drug by modifying factors such as
absorption, distribution, bio transformation and elimination.

GENETIC FACTORS

- individual variation in response to the effects of drugs may occur because of genetic
differences between two individuals.

TIME OF ADMINISTRATION

- the time of day or month that a drug is administered has been shown to affect the
pharmacological response of clients to specific drugs.

Example: corticosteroids often are more effective if given in the morning than at night
TOLERANCE

- considerable variation exists in the ability of different clients to become tolerant to the effects
of certain drugs, particularly narcotic analgesics and other CNS depressants.

-This may account for the dramatic differences in the dosage of a particular drug required to
elicit a given level of pharmacological response in clients

ENVIRONMENTAL FACTORS

- Exposure to very hot or cold environmental temperatures may influence an individual's

response to drug therapy.

Herbal Therapies and Interaction

HERBS

- Herbal medicine has been used since prehistoric times and is used today by up to 80% of the
worlds' population.
- It involves the use of natural plant substances to prevent and treat disease.
- The latter part of the 1990’s and into the twenty-first century has seen an increased use of
herbal supplements by people believing these substances can prevent and cure disease.
- As a result, in 1998 the World Health Organization (WHO) first published Guidelines for the
Appropriate Use of Herbal Medicines (WHO, 2010).
- Historically, herbal medicines has been associated with the Chinese and frequently is used in
conjunction with acupuncture, but associating all herbals with Chinese medicine narrows the
user's focus.
- Currently, herbals are sold in nutrition stores, major drug chains, as well as discount retail stores
wherever vitamins are sold.
- Of primary concern to health care professionals is that herbals are not regulated by the FDA,
and thus their safety and efficacy have not been reliably established.
- Herbal treatment claims range from the treatment and prevention of heart disease to adjuncts
to cancer prevention and therapy.
- Some of the herbs and their uses are familiar to many people, such as aloe Vera, garlic, ginseng,
St. John's wort, gingko, echinacea and saw palmetto.

NURSING IMPLICATIONS

- Because of the increased use of herbal medicine in our society, nurses need to be sure to
address this matter during the assessment of all clients.

Two important facts health care professionals need to remember are :

1. Herbals are not regulated by the FDA.

2. Herbals, like drugs, are chemicals, and consequently, chemically have an influence on the body.
* Nurses need to be familiar with herbals in common use, and should ask clients if they use herbals,
what herbals they use and how often, and assess the client's knowledge of why they are taking these
supplements.

*The nurse also needs to assess the clients for the presence of potential adverse effects associated with
the use with the use of the specific herbal medicines.

*Reporting the information received to the health care provider is an important nursing action that can
influence the pharmacotherapeutics of medical treatment.

• Another nursing concern is the interaction between herbal and prescription medications, thus
reporting the information received to the health care provider is an important nursing implication.

• Herbal supplements can enhance or decrease the effects of certain drugs, thus the individual
should be instructed not to use these herbal supplements when taking the medications.

• The American Society of Anesthesiologists recommends that clients discontinue their use of
herbals a minimum of 2 to 3 weeks prior to surgery due to the numerous risks associated with surgery
and anesthesiology in the presence of these products.

Drug therapy for Older Adult Clients

- Older adults ( 65 years of age and over) make up about 13% of the US population and represent
the fastest growing segment of the population.
- They consume about 34% of all prescription drugs and purchase 30% of all over the counter
(OTC ) medications.
• Approximately 80% of older adults have at least one chronic illness, and 50 % have at least two.
(CDC, 2010)
• Most of these chronic conditions are medically treated with one or more medication per
condition.
• The Substance Abuse and Mental Health Services Administration ( SAMHSA, 2007) reports “ that
older persons regularly consume on average between two and six prescription medications and
between one to three OTC medications per day.”
• With the combined use of prescription and OTC medications, many older adults take 10 drugs
per day.
• Is the term used for multiple medications.
• This term is used when too many medications are used by clients, when more drugs are
prescribed than is clinically warranted or even when all prescribed medications are clinically
indicated.

Polypharmacy

Pharmacokinetic Differences in Older Adult Client

• Reduced gastric acidity because of the gradual reduction in production of hydrochloric acid in
the stomach that may affect the way tablets or capsules dissolve.
• Gastric emptying is slower because there is a decline motor tone and motor activity in GIT.
 • Older adults have a tendency for constipation

Absorption

• Total body water (TBW) content is decreased, resulting in diminished volume of distribution of
some water-soluble medications.
• Total body fat content is increased
• Age related loss of muscle tone due to atrophy
• There is a general decrease in protein-binding capability

Distribution

• The levels of enzymes are decreased because of the decline in liver function with age.
• Liver blood flow is reduced thus, there is a decline in the body’s ability to transform active drugs
into inactive metabolites.
• There is an age-related decrease in liver volume
• Older adults are more likely to experience hepatotoxicity

Metabolism

• Glomerular filtration rate is reduced by 40-50% because of the reduction of blood flow to
the kidneys.
• The number of intact nephrons is decreased.
• Older adults are more likely to experience drug toxicity because of accumulation of drugs.

Elimination

1. Sensory losses affect the older adult’s ability to manage medication programs accurately.

2. Loss of recent memory affects self-care.

3. Medication problems increase with the use of multiple pharmacies and health care providers.

Factors Related to Drug Problems

4. As the number of drugs taken increases, medication errors increase

5. Use of nonprescription drugs, sharing medications, hoarding drugs, and dietary factors are all
related to drug problems in the older adults.

6. Communication difficulties also lead to drug problems.

Factors Related to Drug Problems

1. Take a history of allergies and current use of prescription and nonprescription drugs.

2. Identify potentially inappropriate medications

3. Obtain baseline vital signs, weight and height

4. Obtain information on sensory functioning, home environment, social support network.

5. Review medications with each client every 6 to 12 months thereafter, and with any medication
change.

6. Closely monitor clients taking psychotropic medications and those taking more than four
medications because they are greater risk for falls.

7. Monitor renal function and collaborate with the health care provider regarding potential
changes in dosages if renal function declines.

Drug Therapy for Pediatric Client

• Providing safe and effective pediatric drug therapy represents a great challenge to the health
professional.
• During the period from birth through adolescence, the pediatric client is continually undergoing
dramatic changes in physical growth, psychosocial development and sensitivity to drugs.

Absorption

- reduced gastric acidity because the gastric acid- producing cells in the stomach are immature
until the age of 3.
- As a result, medications such as enteric- coated tablets, which are dependent on a low pH to
break down, may pass through the digestive tract unchanged.
- Gastric emptying is slower, because peristalsis is irregular.
- Topical absorption is faster because of thinner skin and disproportionate skin surface area
- Because IV medication bypass the absorption step, the action of drugs given using this route is
more predictable

Distribution

- Total body water ( TBW) content is much greater: between 70% and 85% in infants. Percentages
of circulating water are higher in the child, and therefore children require higher doses per
kilogram of weight of water-soluble medications than do older clients.
- The blood- brain barrier is immature, leading more drugs to enter the brain.

Metabolism

- The levels of enzymes are decreased because of the immaturity of the liver.
- Children ( age 2-6 years) have higher metabolic rates and thus may require higher levels of
medication, especially older children, whose livers have established microsomal enzymes.

Elimination

- Glomerular filtration rate is approximately 30-50% less than an adult because of immaturity of
the kidneys
- Tubular secretion and reabsorption are decreased, due to renal immaturity
- Perfusion to the kidneys is decreased
 - Urine pH is lower in an infant, as well as the capacity to concentrate urine, resulting in
medications circulating longer and having the potential of reaching toxic levels. After the first
few weeks of life, the kidneys have the acidifying ability of the adult.

Classification of Pediatric Clients

Age Classification

< 36 weeks of gestation Premature or preterm infant

< 1 month. Neonate or newborn infant

1 month to 12 months Infant

1 to 3 years. Toddler

3 to 6 years Preschooler

6 to 12 years. School age child

12 years to 20 years Adolescent

Determining Pediatric Dosages

- Establishing an appropriate drug dosage for a pediatric client is a complex task.

- Traditionally such calculations were based upon the age or weight of a child as compared with
those of a normal adult.

Determining Pediatric Dosages

- Most medications for children are calculated based on the child’s weight until the child attains
adult weight
- Calculation of body surface area (BSA) by the use of nomogram that combines height and weight
data seems to provide fairly good correlation to appropriate pediatric dosage.

1. The nurse's approach to a child must be based on a knowledge of growth and development and on
the individual needs and preferences of the child.

2. Establish a trusting relationship with the child.

3. Always be honest about what is unpleasant or painful, including mentioning the potentially
unpleasant taste of an oral medication.

4. Use a kind but firm approach to the child.

5. Explain the procedure to the child in terms that are easily understood.

6. Obtain information from the caregivers about family and personal history of allergy.

7. Consent must be obtained from caregivers before medication administration

8. Avoid mixing medications into essential foods or milk. As this may cause the child to avoid these
foods.
9. Never tell children the medication is candy or deceive them about what they are taking.

Poisoning

• Poisoning is one of the leading causes of injury and the fourth highest cause of death in children
between the ages of 1 year and 5 years.
• The most common medication ingested is acetaminophen.
• About 90% of all poisonings in children take place in the home, and most are preventable.

Poisoning Prevention

• Prevention is the preferred means of reducing accidental poisonings in children.

• The nurse can play a major role in making parents aware of the ways they can protect their
children.
• Nurses in institutional and community settings should provide instruction and guidance for
parents and child caregivers.
• One successful approach in reducing the incidence of childhood poisoning is conducting
educational programs that teach the child to stay away from hazardous locations or dangerous
products by labeling dangers with an easily identifiable symbol.

NURSING PROCESS IN PHARMACOLOGY

Process:

» Assessment

» Nursing diagnosis

» Planning (with outcome criteria)

» Implementation

» Evaluation

Sample Nursing Care Plan related to Drug Therapy

» This sample presents information useful for developing a nursing process-focused care plan for
patients receiving medications.

ASSESSMENT

• Data collection
o Subjective, objective
o Data collected on the patient, drug, environment
• Medication history
• Nursing assessment
• Physical assessment
• Data analysis
 • OBJECTIVE DATA:
• - Include information available through the senses
• - sources of data are the chart, laboratory test results, reports of diagnostic procedures, health
history, physical assessment and examination findings
• Other examples include age, height, weight, allergies, medication profile, health history
• SUBJECTIVE DATA :
• - all spoken information shared by the patient such as complaints, problems, or stated needs
(patient complains of dizziness, headache, vomiting)

Assessment:

1. Take a medication history including current use of prescription and OTC agents
2. Assess the client’s understanding about illness, including past experience
3. Conduct a physical assessment
4. Obtain information about social networks and resources

Safe Nursing Practice:

» Once data about the patient and drug have been collected and reviewed, the nurse must critically
analyze and synthesize the information.

Analysis of Data:

» - are prioritized in order of critically based on patient needs or problems.

» Actual responses are always ranked above nursing diagnoses that involve only risks.

» Judgment or conclusion about the need/problem (actual or at risk for) of the patient

» Based upon an accurate assessment

Nursing Diagnosis

» Nursing diagnoses related to drug therapy may include the following:

- Ineffective health maintenance

- Noncompliance related to drug regimens
- Deficient knowledge (illness and its treatment)
- Ineffective management of the therapeutic regimen
- Risk for injury

» This includes identification of goals and outcome criteria

» The major purpose of the planning phase are to prioritize the nursing diagnoses and specify goals and
outcome criteria, including time frame for their achievement.

» Patient- oriented outcome criteria must apply to any medications the patient will receive.

Planning

• Identification of goals and outcome criteria

• Prioritization
 • Time frame

Goals

• Objective, measurable, realistic

• Time frame specified

Outcome criteria

• Specific standard(s) of measure

• Patient oriented

Diagnosis and Planning:

1. State relevant nursing diagnoses

2. Identify desired outcomes of nursing intervention
3. Focus on:
- Why the drug is needed?
- How the drug will be administered?
- Common indications of adverse effects
- Other nursing measures that will enhance the likelihood of achieving desired outcomes.
• Requires constant communication and collaboration with the patient and with members of the
health care team involved in the patient’s care, as well as the family members.
• The nurse needs to know and understand all of the information about the patient.
• “Rights of giving medications”

Implementation:

Preparing Drugs for Administration:

1. Ensure cleanliness of hands, work area and supplies

2. Ensure availability of supplies
3. Ensure adequate lighting
4. Decrease environmental distractions
• Occurs after the nursing care plan has been implemented
• It is systematic, ongoing and a dynamic phase of the nursing process as related to drug therapy
• It includes monitoring of goals and outcome criteria, as well as monitoring the patient’s
therapeutic response to the drug and its adverse effects and toxic effects.

Evaluation

Sample Problem:

The day shift charge nurse is making rounds. A patient tells the nurse that the night shift nurse never
gave him his medication, which was due at 11 PM. What should the nurse do first to determine whether
the medication was given?

1. Call the night nurse at home.

2. Check the Medication Administration Record.
3. Call the pharmacy.
 4. Review the nurse’s notes.

Sample Problem:

The day shift charge nurse is making rounds. A patient tells the nurse that the night shift nurse never
gave him his medication, which was due at 11 PM. What should the nurse do first to determine whether
the medication was given?

1. Call the night nurse at home.

2. Check the Medication Administration Record.
3. Call the pharmacy.
4. Review the nurse’s notes.

1. Client Teaching is an important nursing function that enables the client to engage in self-care.

2. To be effective, teaching must take into account the client’s readiness to learn, unique
characteristics and life situation.

3. Teaching makes use of the nursing process

4. Clients should possess general knowledge of their illness and its treatment.

Client Teaching:

• Ideally, cooperation with treatment means that all medication doses are taken correctly for the
prescribed length of therapy.
• Some reasons for lack of cooperation include inadequate understanding of the illness, cost of
medication, the development of adverse effects, and forgetfulness.
• A number of measures can be taken to foster the likelihood of cooperation.
• These include :
- educational programs
- memory aids
- alterations in the number and doses of medication
• The nursing process is an important means of promoting cooperation.

Dosage Calculations

Three systems of measurement are used during the calculation, preparation, and administration of
medicines.

1. Metric System or SI

- Was invented in France in the late 18th century

- Most widely used system of measure
- Based on decimal system, so all units are determined as multiples of 10.
- gram as basic unit of solid(weight),
- liter as basic unit of liquid volume
 - Meter as basic unit of length

Metric unit most frequently used

• 1 g = 1000 mg
• 1 kg = 1000 g
• 1 L = 1000 mL
• 1 mg=1000 mcg

2. Household system

- Measuring system that is found in recipe books

- Primarily used by patients who take medication at home, however they are least accurate
- Teaspoon as basic unit of fluid measure
- Pound as basic unit of solid measure

Common Household Equivalents

1 quart = 4 cups

1 pint = 2 cups

1 med size glass= 8 ounces

1 teacup = 6 ounces

1 tablespoon = 3 teaspoons

1 teaspoon = approximately 5 ml
3. APOTHECARY SYSTEM

• Originated in Greece, but eventually it made its way to England where it was used during the late 1600s
• Is an ancient system, means “pharmacist” or druggist
• Very old system of measure
• Uses Roman numerals to denote amount ex: 15 grains written as “gr xv”
• Minim as basic unit of liquid volume
• Grain as basic unit of solid measure

Eg:

• grains – 1/150

CALCULATING MeDICATION DOSAGeS (Interpreting Drug Prescriptions)

Example 1:

Caps. Diphenhydramine (Benadryl) 25 mg q4h po

Interpretation:

“Give the client one 25 mg capsule by mouth every 4 hours”

Example 2:

Elixir acetaminophen (Elixir Tylenol) 80 mg tid pc and at bedtime po

Interpretation:

“Give 80 mg of elixir acetaminophen by mouth three times a day after meals and at bedtime.”

Abbreviation Latin derivation English

G Gramma Gram

Gr Granum Grain

Gtt Gutta Drop

Lb Libra Pound

mL Milliliter

No Numerus Number

Qs Quantum sufficient

Timing of Administration

Abbreviation Latin deruvation English

a Ante Before

ac Ante cibum Before meals

am Ante meridian Before noon

bid Bis in die Twice a day

h Hora Hour

p Post After

pc Post cibum After meals

pm Post meridian After noon

prn Pro re nata Whenever necessary

q Quaque Every

qid Quarter in die 4 times a day

tid ter in die 3 times a day

Values of Single Roman Numbers

Roman Numerals Value

I or i 1

V or v 5

X or x 10

L or l 50

C or c 100

D or d 500

M or m 1,000

General Methods for Drug Calculation

1. Ratio & Proportion

2. Fractional Equation
3. Basic Formula
4. Body Weight
5. Body Surface Area used for pedia patient

Terms:

� Route : how the medication is entering the body. PO? IV? Topical?
� Medications : The actual compound that is completing the desired effect
� Dose: How much of this medication is being administered?
� Vehicle: The way/size the medication is

Ratio and Proportion

• Ratio – the relationship of two quantities

• It may be expressed in the form 1:10 or 1: 2,500 or it ay be expressed as a fraction – 1/10 or 1/2,500
• Proportion- is formed by using two ratios that are equal.
Example 1

An order is written for 10 grains of aspirin (gr x, aspirin). The tablets that are available each contain 5 grains.

How many tablets should be given? What will be your answer?

First, set up the equation:

5 gr = 10 gr
1 tablet x
Cross multiply the ratio:

5 (gr) X = 10 (gr)(tablet)

Rearrange and cancel the units and numbers :

X = 10 (gr)(tablet)
5 (gr)
X = 2 tablets (answer)

Example 2

An order is written for 0.05 g Aldactone to be given orally (PO). The Aldactone is available in 25 mg. tablets.

How many tablets would you have to give?

First you will need to convert the grams to milligrams.

1g = 0.05 g
1000 mg X
Cross multiply:

1 (g) X = (0.05 x 1000) (g)(mg)

Simplify:
X = 50(g)(mg)
1 (g)
X = 50 mg (answer)

25 mg = 50 mg

1 tablet X

25 (mg)X = (50x1) (mg)(tablet)

X = 50 (mg)(tablet)

25 (mg)

= 2 tablets (ans)

Fraction

• Sometimes the desired dose will be a fraction of a tablet or capsule, like ½ or ¼ .

• Some tablets come with score markings that allow them to be cut.
• Pill cutters are readily available in most pharmacies to help patients cut tablets appropriately.

Oral Drugs

• Frequently, tablets or capsules

• For solid and liquid preparation

D (desired dose)
____________ X Vehicle = amount to give

H (amount of drug on hand) Or

Dose desired x V = amount to give

Stock on hand

For Solid:

• A health care provider orders that a patient receive 1 g. of ampicillin. The ampicillin bottle states that each tablet in the bottle contains 0.5 g

• Sol:

• D = 1.0 g = 2 tablets
S 0.5 g

If the dosage on hand and dosage ordered are both in the same system of measurement, but they are not in the same unit of weight within the system, the
units of weight must first be converted.

The health care provider orders 1000 milligrams (metric) of ampicillin.

On hand is 0.25 g (metric) per tablet

Dose desired = 1000 mg = 4 tablets

Dose on hand 250 mg
For Liquid

- The order is for Potassium Chloride (KCl)20 mEq. The bottle is labeled KCl elixir 10 mEq/mL.

How many mL. will be given?

Answer : 2 mL

For capsule

- The order reads: Phentoin sodium capsules (Dilantin) gr. v orally.

 - Available is a bottle labeled Dilantin 100 mg.per capsule.

How many capsules will be given?

• 1gr.= 60 mg

• Answer : 3 caps

For parenteral

Order reads:

• Furosemide (Lasix) 35 mg IV. The vial is labeled 40 mg=4 ml.

• How many mL. should be given?
• Answer: 3.5 mL

Problem:

o An order has been written for 75 mg meperidine to be given intramuscularly (IM). The vial states that it contains meperidine, 1.0 mL= 50.0 mg.
o How much should the nurse administer?
o Answer : 1.5 ml.

For units(some medications such as heparin and penicillin are ordered in units)

• The ordered is penicillin 750,000 units. The vial reads 300,000 units/2 ml.
• How many mL will be given?
• Answer : 5 ml

�The order is penicillin 50,000 units. The vial reads penicillin 500,000 units. Add 4.3 mL to yield 5mL.

�Give 0.5 mL.

Pediatric Dosage Calculations

Pediatric Considerations

• A child’s body may handle a drug differently in all areas of pharmacokinetics- absorption, distribution, metabolism and excretion.
• The responses of the child’s organs to the effects of the drug also may vary because of the immaturity of the organs.

Methods of Pediatric dose

a. Clark’s rule
b. Body surface area (BSA)
c. Dosage based on weight

Clark’s Rule

• Uses the child’s weight to calculate the appropriate dose and assumes that the adult dose is based on a 150-lb person.

• Uses Weight in Lbs, NEVER in Kg

Child’s dose:

= Childs Weight (in pounds) x average adult dose

» 150 pounds

Problem

-The usual adult dose of Benadryl is 50 mg. What would be the safe dose for a child weighing 27 lb.

Solutions:

= 27 lbs x 50 mg

150 lbs.

= 1,350 mg

150

= 9 mg
Body surface area (BSA): most accurate method for calculating pediatric dosages.

Formula:

child’s dose = Surface area (m2) x adult dose

1.73 m2

The adult dose is 100 mg/mL. Demerol. The child weighs 20 kg and is 40 inches tall. BSA is 0.77m2

Ans:

= 0.77 m2 x 100 mg/ml

1.73 m2

= 77 mg/ml = 44.5 mg/ml

1.73
Dosage based on weight
•Most medications for pediatric clients are done by child’s weight in order to more accurately dose.

Example:

•A 1.5 year old child is prescribed an amoxicillin suspension. The dose prescribed is 40 mg/kg/day divide into equal BID doses. The suspension is available in a
400 mg/5ml suspension. What is the dose in ml? The child weighs 2.2 pounds.

4 Steps to follow:

Step 1 – Convert pounds to kg.

Step 2 – Calculate the dose in mg

Step 3 – Divide the overall dose by the frequency (BID,TID,etc.)

Step 4 – Calculate the dose in ml or tablets (follow the same formula with adults)

Step 1 – 22 lbs. = 10 kg
 2,2 lbs
Step 2 – 10 kg x 40 mg/kg/day = 400 mg/day

Step 3 – 400 mg/day = 200 mg/dose

2 (BID)

Step 4 - D x V - 200 mg x 5 ml

S 400 mg

= 0.5 x 5 ml

= 2.5 ml

Intravenous Fluids Calculations

Intravenous (IV) solutions (fluids) consist of a liquid (solvent) containing one or more dissolved substances (solutes).

Administration set

- used to deliver a specified volume of solution are different, depending on the company manufacturing the set.

Macrodrop

• a chamber that delivers large drops

• Adult giving sets and drip chambers are calibrated such that 20 drops of fluid = 1 mL.

Dosage calculation for IV meds

1. Macrodrop

- More commonly used in adult IVF

- In order to calculate the flow rate, need to know the drop factor: 10, 15, or 20 gtt/mL

2. Microdrip

- a chamber that delivers small drops

- All microdrip chambers deliver 60 drops (gtt) per mL.
2. Microdrop

- More commonly used for children, elderly or critically ill where exact control is required
- Drop factor is always 60 gtt/mL

The manufacturer of the macrodrip administration set has standardized the drops per milliliter called the drop factor (DF) for a specific brand of administration
set as follows:

A specific brand of administration set as follows:

Company Name Drop factor (gtt/mL)

Abbott 15

Baxter International 10

B. Braun 15

IVAC 20

Calculation of Flow rates

a. Milliliters per Hour (mL/hr)

mL/hr = total number of mL ordered

Number of hours to run
b. Milliliters per Min (mL/min)

mL/min = total mL or volume

total mins to run
Problem

1.Infuse 1000 mL Lactated Ringer’s (LR) solution over 10 hours.

Sol: ml/hr = 1000 ml

 10 hrs
= 100 ml/hr

Calculate the following problems:

Health care Duration

Providers Order of Infusion

Rate(mL/hr)

1000 mL 5% dextrose 12 hrs = 1000mL = 83.3 or 83 ml/hr

in water 12 hrs

1000 mL Lactated 6 hrs. = 1000mL = 166.6 or 166 ml/hr

Ringer’s 6 hrs

500 mL 0.9 sodium 4 hrs = 500mL = 125 ml/hr

Chloride 4 hrs

Calculating Rates of Infusion for other than 1 hour

mL/hr= Total volume (milliliters) to infuse x 60 min/hr

Time

Compute:
1. 50 mL 0.9 Na Cl with ampicillin 1 g for 20 mins

2. 150 mL D5W with gentamicin 80 mg to run for 30 mins

Drops per Minute (gtt/min)

gtts/min= Total volume (mL) to infuse x drop factor Time (number of mins)

Directions:

- Use a drop factor of 15 gtt/mL for volumes of 100 mL or more per hour;

- Use a microdrip (60gtt/mL) for volumes below 100/hr

Calculate the following problems

Health care Duration Providers Order of Infusion

Rate(gtt/min)

• 125 mL D5W 60 min = gtt/min

• 100 mL LR 60 min = gtt/min

• 50 mL 0.9 NaCl 20 min = gtt/min

• - pls solve this before turning to the next page---

Solutions

1. 125 ml x 15 gtts/ml

60 mins

= 1,875 gtts = 31.2 or 31 gtts/min

60 min

2. 100 ml x 15 gtts/ml

60 min

= 1,500 gtts = 25 gtts/min

60 min

3. 50 ml x 60 gtts/ml

60 min

= 3,000 gtts = 150 gtts/min

60 min
Example

• The order is for 1000 mL NS over 8 hours; drop factor is 10 gtt/mL

• What is your answer?

 Solution:

• 1000 ml x 10 gtts/ ml

• 480 mins * * ( 8 hrsx 60 mins = 480 mins)

• = 10,000 gtts

• 480 mins

• = 20 .83 or 21 gtts/min
• The same formula can be used for Ivs requiring microdrip rates or the following formulA can be used:

• mL / hr = microdrops / min

• Microdrop – 60 microgtts/ml

• Hour is 60 mins
Example

Order is for 1000 mL D5NS over 24 hours. Drop factor is 60 gtt/ml

Try solving this!

 Solutions
• 1,000 ml x 60 gtts/ ml

• 1,440 mins (24 hrs x 60 mins)

= 60,000 gtts

• 1,440 mins

• = 41.66 or 42 gtss/min
Doctor’s order: Infuse 1200 mL of 0.45 % Normal Saline

at 125 mL/hr. to run 8 hrs.

Drop factor: 12 gtt/min. How many gtt/min will you

regulate the IV?