Intro to Pharmacology
Welcome to Pharmacology
Pharmacology means “medicine” and “study”
essentially the study of medicine
Pharmacology is a discipline devoted to patient
therapy though the use of drugs. It is an expansive
topic utilizing concepts from human biology,
pathophysiology, and chemistry.
pharmacology and therapeutics
Therapeutics is the discipline dealing with the
treatment of suffering and the prevention of
Pharmacotherapeutics is the useful application of
drugs for the purpose of fighting disease.
Both areas are at the core of the nursing profession.
Therapeutic agents may be classified as traditional
drugs, biologics or alternative therapies.
Drugs are chemical agents used to treat diseases in the
body. Biologic drugs are substances produced naturally
by a living organism.
Alternative therapies involve herbal supplements and
certain techniques deemed to be less conventional.
RX vs OTC
Drugs are available by prescription or as over the
counter (OTC) medication.
There are two major methods of dispensing drugs:
purchase of prescriptions drugs with a physician’s
order and purchase of OTC drugs which do not
require a physician’s order.
There are advantages and disadvantages to both
methods of dispensing.
Food and Drug Administration (FDA) was an agency
established by the U.S. Department of Health and
Human Services to help regulate over prescription
drugs, OTC drugs, as well as medical devices.
Drug approval involves four stages: pre-clinical
investigation, clinical investigation, submission of a New
Drug Application with review, and post-marketing
surveillance. Clinical phase trials must be completed
before drugs are approved for public use.
Drug Classes and Schedules
Drugs may be organized by their therapeutic or
Two common ways to classify drugs are by therapeutic
classification and pharmacological classification.
Therapeutic classes are based on a drug’s clinical
Pharmacological classes are based on a drug’s mechanism
Prototype drugs are used to compare drugs within the same
chemical, generic, and trade names
Drugs may be described by a chemical, generic or
Chemical names are precise but complicated and
difficult to remember. Drugs have only one generic
name that is usually short and easy to remember.
The company marketing the drug assigns trade
names. Drugs may have multiple trade names.
Generic and Brand name
Generic drugs are less expensive than brand name
drugs, but they may differ in their bioavailability.
Generic drugs are less expensive and may be
substituted for brand named products in most states
if the prescriber does not object. Generic drugs
may differ from their trade name counterparts with
respect to their bioavailability. This may affect the
safety and effectiveness of drug therapy.
I High Abuse Potential
High Physical Dependence
High Psychological Dependence
Heroin, LSD, Marijuana
II ex. Morphine, PCP, cocaine, methadone
used therapeutically with prescription
• Scheduled Drugs
III Moderate Abuse Potential
Moderate Physical Dependence
High Physiological Dependence
ex. Anabolic steroids, codeine,
hydrocodone, some barbituates
ex. OTC cough medicines with codeine
Principles of Drug Administration
Allergic Reaction: acquired hyperresonance of body
defenses to a foreign substance (allergen).
Anaphylaxis: severe type of allergic reaction that
involves the massive, systemic release of histamine
and other chemical mediators of inflammation that
can lead to life-threatening shock.
Side Effects vs Adverse Effects
Fatal Drug Reactions
Toxic Epidermal Necrolysis (TEN)
Widespread epidermal sloughing
Epidermal detachment of skin and mucous membranes
Multisystem organ involvement
Assoc. with anticonvulsants, Abs, and other drugs
dilantin, carbamazepine, Bactrim
Fatal Drug Reactions
Causes similar to those that cause TEN
Begins within the first 1-14 days of pharmacotherapy
Starts as signs of URI with chills, fever and malaise
Generalized blisterlike lesions follow within a few days
Skin sloughing of 10% of the body
Three Checks – Safety First
• Three checks of drug administration:
– Checking the drug with MAR or the medication
information system when removing it from the
medication drawer, refrigerator or controlled substance
– Checking the drug when preparing it, pouring it, taking
it out of the unit-dose container, or connecting the IV
tubing to the bag.
– Checking the drug before administering to the client.
Five Rights of Drug Adminstration
Right client (2 patient identifiers)
Right route of administration
Right time of Delivery
Principles of Drug Administration
The nurse must have a comprehensive knowledge of
the actions and side effects of drugs before they
The nurse assumes great responsibility for drug
A firm knowledge of pharmacology is required
before a drug is administered. This understanding
takes into account the actions and side effects of the
drug as well as the physical and emotional needs of
Compliance: taking medication in the manner
prescribed by the practitioner, or in the case of OTC
drugs, following the instructions on the label.
STAT order: Refers to any medication that is needed
ASAP: Available within 30 minutes
For pharmacologic compliance, the patient must understand
and personally accept the value associated with the
prescribed drug regimen. Understanding the reasons for
noncompliance can help the nurse increase the success of
The nurse may be conscientious regarding all of the
principles of medication administration but these strategies
are of little value unless the patient agrees that the
prescribed medication regimen is personally worthwhile. The
nurse must understand factors which decrease compliance
such as expense, annoying side effects, and self-dosing with
Single Order: Only once
PRN: As needed basis
Routine orders: carried out within two hours of the
time it is ordered by the physician.
Standing order: Written in advance of a situation
that is carried out under specific circumstances.
Ex. Tylenol 325 mg PO Q 6hrs PRN headache
Systems of Measurement
Systems of measurement used in pharmacology include
the metric, apothecary, and household systems.
Doses are usually written in terms of the metric system
such as milligrams or milliliters. The older apothecary
system is rarely used. The household system (which
employs the teaspoon and tablespoon method) remains
in common use. Therefore, the nurse must be able to
convert between the apothecary and metric systems.
Parental Drug Administration
Enteral Drug Administration
Topical Drug Administration
Otic, nasal, vaginal, rectal
• Must have a comprehensive knowledge of the
actions and side effects of drugs before they are
administered to limit the number and severity of
adverse drug events.
• The 5 rights and 3 checks are guidelines for safe
drug administration which is a collaborative effort
between nurses, physicians, and other healthcare
• The enteral route includes medications given orally and
those administered through nasogastric or gastrostomy
• Oral medication administration through tablet, capsule,
and liquid formulation is the most common, convenient,
and usually, the least costly of all the routes. Absorption
is generally slow and the drug must be stable in the
presence of digestive enzymes. The sublingual and
buccal routes are enteral routes less commonly used.
• Topical drugs are applied locally to the skin or
membranous linings of the eye, ear, nose respiratory
tract, urinary tract, vagina and rectum.
Topical medications may be applied for either topical
or systemic effects. Most topical routes provide for slow
absorption, thus they produce few systemic side effects.
Topical routes include dermatologic, instillation, and
Parental administration is the dispensing of medications via a
needle, usually into the skin layers (ID), subcutaneous (SQ),
intramuscularly (IM), and into veins (IV).
Parenteral administration results in a rapid onset of drug action.
Because of the possibility of introducing microbes directly into the
body, parenteral routes are considered invasive and require aseptic
technique. Parenteral administration includes the ID, SC, IM, and IV
Pharmacokinetics focuses on the movement of drugs
throughout the body after they are administered.
Pharmacokinetics is an area of pharmacology dealing
with how drugs are handled by the body. It describes
the barriers that drugs must penetrate to achieve
therapeutic success. The four components of
pharmacokinetics are: absorption, distribution,
metabolism, and excretion.
The physiological properties of plasma membranes
determine movement of drugs throughout the body.
To be distributed to body tissues, drugs use diffusion
and active transport to cross biological membranes.
Drugs that are small, uncharged, and lipid soluble
are distributed more completely than those that are
large, ionized, and water-soluble.
Absorption and its rate
Absorption is the process of moving a drug from the
site of administration to the bloodstream.
Many factors affect drug movement including the
type of drug formulation, drug-drug and drug-food
interaction, GI and bloodstream factors, and
properties of cellular membranes. Lipid solubility,
ionization characteristics, and the pH of the
dissolving or transport medium will also affect drug
Distribution: involves the transport of pharmacologic
agents throughout the body>
The determining factor is the distribution of the
amount of blood flow to the body tissues.
The heart, liver, kidneys and brain receive the most
Blood Brain Barrier
A drug’s distribution is affected by variables such as
lipid solubility, degree of ionization, and plasma
The blood-brain and fetal-placental barriers represent
areas in the body where drug distribution may be
Lipid-soluble and non- ionized drugs easily cross these
barriers; water-soluble and ionized drugs do not.
Excretion processes remove drugs from the body.
The kidneys, lungs, sweat glands, mammary glands,
and biliary system are the major tissues eliminating
drugs from the body.
The main organ involved with excretion is the
Enterohepatic recirculation is responsible for
circulating bile and certain drugs back into the
bloodstream from the gastrointestinal tract.
• Rate at which drugs are excreted determines their
concentration in the bloodstream and tissues.
• The concentration of the drugs in the bloodstream
determines the duration of action.
• Pathological states such as liver disease and renal
failure often increase the duration of action in the
body because they interfere with the natural
– Dosing must be adjusted in these cases
Pharmacodynamics is the area of pharmacology
concerned with how drugs produce change in
patients and the differences in patient responses to
Pharmacodynamics explains how drugs produce
changes in the body.
Therapeutic and Toxic Range
• Minimum Effective Concentration
– The amount of drug required to produce a therapeutic
• Toxic Concentration
– The level of the drug that will result in serious adverse
• Therapeutic range
– Plasma drug concentration between the minimum
effective concentration and the toxic concentration
The therapeutic index is a value representing the
margin of safety of a drug.
The larger a medication’s therapeutic index, the
greater is its margin of safety.
• Maintenance dose
– Dose given to keep the plasma drug concentration in the
• Loading dose
– A higher concentration of medication given to prime the
blood stream with levels significant to quickly induce a
– Length of time required for the plasma concentration of a
medication to decrease by half after administration.
Magnitude of maximal response that can be produced
from a particular drug.
A drug that is more potent will produce a therapeutic
effect at a lower dose, compared with another drug in
the same class.
Aspirin 650 mg versus Ibuprofen 200 mg
Ibuprofen more potent, same efficacy
Potency vs Efficacy
Potency relates to the dose of medication required
to produce a particular response; the higher the
potency, the less dose is needed to produce a
Efficacy refers to the magnitude of maximal
response: the higher the efficacy, the greater the
response. In most cases, the efficacy of a drug is
more important to the patient and nurse than is the
Drug Administration Throughout the
In order to contribute to safe and effective
pharmacotherapy, it is essential for the nurse to
comprehend and apply fundamental concepts of
growth and development.
Nurses must possess an understanding of what is
considered normal, in terms of growth and
developmental patterns, so that deviations from the
norm can be identified and health pattern impairments
can be appropriately addressed. The very nature of
pharmacology requires that the practitioner consider
the specifics of age, growth, development, and weight
in relation to pharmacokinetics and pharmacodynamics.
Pharmacotherapy during pregnancy should be
conducted only when the benefits to the mother
outweigh the potential risks to the fetus.
Pregnancy Categories guide the practitioner in
prescribing drugs for these patients.
Breastfeeding patients must be aware that drugs and
other substances can appear in milk and affect their
Chemicals derived from foods and drugs ingested by
the mother may traverse the placental barrier and
affect the developing baby.
An in-depth nursing and pharmacologic history and
prenatal assessment are vital so that drugs can be
eliminated, substituted or dosages adjusted.
Pregnancy Categories have been developed by the
FDA to assess potential risk to the fetus. Breast-feeding
patients must be aware that drugs and other substances
can appear in milk and affect their infant.
• Pregnant client
– Distribution and Metabolism
• Increase Cardiac Output
• Increased Blood Flow
• Change in regional blood flow
• Alterations in lipid levels
• Hormonal changes, pressure on blood supply
• Gastric emptying delayed
• Gastric acidity decreased
• Increased Resp. system
Pregnant Client – Teratogenic effects
Increased kidney flow by 40%
Teratogens-agents that cause fetal malformation
Especially in the first trimester
Lactating Client-many OTC, herbal supplements and meds are
excreted in the breast milk
During infancy, pharmacotherapy is directed toward the
safety of the child and teaching the mother how to
properly administer medications and care for the infant.
Infants require special treatment due to their small size
and their immature physiologic and biochemical
Mothers breastfeeding their infants must be counseled
regarding the possibility of drugs entering their milk
and affecting their baby.
Drug administration to toddlers can be challenging.
Short, concrete explanations followed by immediate drug
administration are usually best for the toddler.
During the toddler stage, there is a tremendous sense of
curiosity and this becomes a major concern for medication
safety as well as household product safety. Toddlers can
swallow liquids and usually chew tablets. Restraint may be
required, particularly when administering parenteral
Preschoolers and younger school age
Preschool and younger school age children can begin to
assist with medication administration.
During the early school years, children begin to realize
the benefits of medications and the reasons why
medications are needed.
The nurse should give the child a sense of control over
drug administration, while still being firm and giving the
child praise for cooperation.
Pharmacologic compliance in the adolescent is dependent
upon an understanding and respect for the uniqueness of the
person in this stage of growth and development.
Adolescents are very concerned with physical appearance
and peer approval. Common indications for
pharmacotherapy in this group includes: skin conditions,
headaches, menstrual irregularities, and sports injuries. The
use of tobacco and illicit drugs is a major concern. The nurse
should respect a teen’s need for independence and privacy.
Young adults comprise the healthiest age group and
generally need few prescription medications.
Middle age adults begin to suffer from stress-related
illness such as hypertension.
Younger and middle-aged adults generally need little
pharmacotherapy, relative to older adults.
In females, contraception and complications associated
with pregnancy are of major concern.
In the middle-aged adult, cardiovascular concerns such
as hypertension become important.
Older adults take more medications and experience more adverse
drug events than any other age group. For drug therapy to be
successful, the nurse must make accommodations for age-related
changes in physiological and biochemical functions.
The older adult is faced with numerous physical challenges, which
become targets for pharmacotherapy. Changes in liver and kidney
function make pharmacotherapy more risky. Cardiovascular disease
becomes a major indication for pharmacotherapy.
Elderly and Medication Use
Monitor for nutritional status and hydration
Liver and Kidney Function
Herbal and Alternative Therapies
• Familiarize yourself with the Best-Selling Herbal
Supplements pg 110
• Familiriaze yourself with the most Common Herb
Drug Interactions pg 113
– Kava Kava
– St. John’s Wort
Nursing Process and Pharmacology
The Nursing Process is a systematic method of problem-
solving and consists of clearly defined steps:
assessment, establishment of nursing diagnoses,
planning care through the formulation of goals and
outcomes, carrying out interventions, and evaluating the
The steps of the nursing process include assessment,
development of nursing diagnoses, identification of
goals and outcomes, planning care, implementing
interventions and evaluating the plan of care.
Pharmacology requires the use of the Nursing Process to
ensure the best possible outcomes for the patient.
Assessment of the patient related to medication
administration includes health history information,
physical assessment data, lab values and other
measurable data. It also includes an assessment of
medication effects: therapeutic, side or adverse
Assessment is the collection of objective and
subjective data. This is acquired starting with the
initial health history and continues on an ongoing
basis during treatment.
Nursing diagnoses are written that address the patient’s
responses related to medication administration. They are
developed after an analysis of the assessment data. The
diagnoses are focused on the patient’s problems or potential
problems and are verified with the patient or caregiver.
After analyzing the assessment data, the nurse formulates
patient-specific nursing diagnoses appropriate for the
medications used. These diagnoses will form the basis for the
other steps in the Nursing Process. Two of the most common
nursing diagnoses that may be established for medication
administration are knowledge deficit and noncompliance.
Goals and outcomes are developed from the nursing
diagnoses that will direct the interventions required by the
plan of care. Goals focus on what the patient should be
able to achieve and outcomes provide the specific,
measurable criteria that nurses will use to measure goal
After gathering patient assessment data and formulating
nursing diagnoses, goals and outcomes are developed and
priorities are established that will assist the nurse in planning
care, carrying out interventions, and evaluating the
effectiveness of that care. Goals and outcomes may be
developed for the short-term or long-term, depending on
the specific situation.
Interventions are aimed at returning the patient to an
optimum level of wellness through the safe and
effective administration of medications. Key
interventions required of the nurse include monitoring
drug effects, documenting medications, and patient
Interventions are aimed at returning the patient to an
optimum level of wellness and limiting adverse effects
related to the patient’s condition. Key components of
implementation include monitoring and documentation
of drug effects, and patient education.
Evaluation begins a new cycle as new assessment
data is gathered and analyzed, nursing diagnoses
are reviewed or rewritten, goals and outcomes
refined, and new interventions are implemented.
Evaluation is the final step of the Nursing Process. It
considers the effectiveness of the plan of care and
interventions in meeting established goals and
Legal and Ethical Issues
The American Nurses Association publishes a list of
ethical principles that nurses can use to guide their
Ethics (the moral principles guiding a person’s
conduct) are learned early in life through religious
affiliations, family, role models, and peers. The ANA
Code of Ethics provides guidance to nurses in their
professional conduct and in decision- making.
Legal and Ethical Issues
Moral principles such as beneficence, non-maleficent
behavior, veracity, autonomy, justice, and fidelity are
necessary for the nurse to apply in medication
When making ethical decisions in clinical practice, the
nurse uses fundamental moral principles. Three of the
most important principles are: promote the most good
for the patient (beneficence), do not harm the patient
(non-maleficent behavior), and allowing the patient the
informed right to choose the course of their care
Legal and Ethical Issues
Nurse practice acts are enacted by every state to
define the scope of practice of professional nursing
and to protect the public.
The State nursing practice acts define the standard
of care for practicing nurses. In essence, they define
what a nurse can and cannot do. Standards of care
state the minimum competency for proficiency in
nursing and should be consulted frequently.
Legal and Ethical Issues
Documentation of medication administration,
including any errors, should be completed
immediately after the patient takes the drug.
Medication use is documented in the MAR. Nurses
frequently check the physician’s orders against the
MAR to be certain the correct drugs have been
A medication error is a preventable error that may
cause or lead to an adverse reaction to the patient.
Causes may include omission of one of the “five
rights” or giving medications based on verbal,
illegible or incomplete orders.
Medication errors can result in serious injury to the
patient and litigation for the nurse and healthcare
agency. The nurse must ensure that orders are
carried out accurately and that every measure is
taken to avoid errors.
It is the ethical and legal responsibility of the nurse to report any
medication errors that might have occurred.
Documentation of medication errors is necessary for patient safety.
Several national organizations contain databases of medication
errors that can assist nurses and healthcare agencies formulate
9.7 Finding strategies to prevent of medication errors involves many
different processes, including the nursing process.
Use of the nursing process can help reduce the
number of medication errors. Nurses should work
and collaborate with others on the healthcare team
to develop agency policies for the storage and
handling of medicines.