Pharmacology: Principles and
Applications
2nd edition
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Slide 0
Chapter 2 critical thinking case of
Basics of Pharmacology
Yvette, a new patient, has been diagnosed
by the physician as hypertensive. The
physician has prescribed two new
medications for her to take. Yvette is also
taking several other medications for
osteoarthritis and allergies; these were
prescribed by another physician, but she
cannot remember all of the names. What
can you do to make certain you have all
the right information about Yvette’s new
medications so that they will not cause
any adverse or toxic reactions?
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Slide 1
Learning Objectives





Providing definitions of the key words using
the appendix or a medical dictionary.
Stating healthcare workers’ responsibilities in
regard to adverse reactions, side effects, and
toxic reactions.
Defining a drug and an ideal drug.
Describing the five fundamental categories of
pharmacology and how these factors
influence medications in the body.
Describing the indications of medications
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Slide 2
Chapter 2
Lesson 2.1
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Slide 3
What is a Drug? What is an Ideal
Drug?



any chemical used for
therapeutic application
can help or harm an
individual
may alter biochemical
function of the body
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Slide 4
What is a Drug? What is an Ideal
Drug? (cont’d.)
Drug components
 active ingredient
 inert ingredient
 vehicle
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Slide 5
What is a Drug? What is an Ideal
Drug? (cont’d.)
Ideal drug:
 produces no side effects or adverse reactions
 produces same effect each time the same
dose is given
 easy to administer
 inexpensive
 easy to pronounce, remember
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Slide 6
What is a Drug? What is an Ideal
Drug? (cont’d.)
No drug is completely safe.
 All drugs cause some side effects or adverse
reactions.
 Drug must be as safe as possible.


Should have no harmful effects when taken in high
doses over a long period of time.
Be aware of a drug’s effects in order to safely
administer medications.
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Slide 7
Five Basic Categories of
Pharmacology
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
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
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Pharmacognosy: origins of drugs
Pharmacokinetics: how drugs are
processed by the body
Pharmacodynamics: actions of drugs on
the body
Pharmacotherapeutics: effects of drugs on
the body
Toxicology: the poisonous effects of drugs
on the body
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Slide 8
Pharmacognosy—The Origins of
Drugs

Historically, drugs came from four basic
sources:





plants
animals
minerals
synthetic substances
Recently, recombinant DNA technology
(gene-splicing) is being used to create drugs.
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Slide 9
Drug Sources—Plants
Source
Drug
Purple foxglove (digitalis)
digoxin
Rose hips
vitamin C
Cinchona bark
quinidine
Opium poppy
morphine, codeine, paregoric
Periwinkle (vinca)
vincristine
Snakeroot
reserpine
Belladonna
atropine, scopolamine
Willow bark
aspirin
Castor bean
castor oil
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Slide 10
Drug Sources—Minerals
Source
Drug
Gold
Salganol, auranofin
Zinc
zinc oxide
Calcium
Os-Cal, Cal-Bid, CitraCal, Rolaids, Tums
Magnesium
Milk of Magnesia, Mylanta, Maalox
Aluminum
Amphojel, Gelusil
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Slide 11
Drug Sources—Animals
Source
Drug
Codfish
cod liver oil
Pancreas of cow or hog
insulin
Stomachs of hogs
pepsin
Animal thyroid glands
thyroid hormone
Placenta
hair products
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Slide 12
Drug Sources—Synthetics
Source
Drug
Inorganic
sulfonamides, oral contraceptives,
barbiturates
Organic
penicillin, cephalosporins
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Slide 13
Drug Sources—Recombinant DNA
Technology
Source
Drug
Insulin
Humulin
Erythropoietin
Epogen
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Slide 14
Pharmacokinetics—How the Body
Processes Drugs
Involves four processes:
 Absorption: movement of a drug from its
administration site into the blood
 Distribution: movement of a drug from the
blood into tissues and cells
 Metabolism: physical and chemical alteration
of a drug in the body
 Excretion: removal of waste products from
the body
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Slide 15
Drug Activity in the Body
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Slide 16
Absorption
Medications are administered by three routes.
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Slide 17
Absorption (cont’d.)
Physical properties that affect absorption rates:
 solubility
 pH
 absence or presence of food in stomach
 fat solubility
 length of contact
 inhalation factors
 drug concentration
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Slide 18
Route of Drug Administration and
Rates
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Slide 19
Distribution


a drug is delivered to
tissues through
blood vessels and
capillaries.
a drug’s effect takes
place in tissues, not
blood vessels.
Modified from Leahy, JM,
Kizilay, PE (1998).
Foundations of nursing
practice. Philadelphia:
Saunders.
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Slide 20
Distribution (cont’d.)
Factors affecting drug distribution:
 permeability of capillaries to drug’s molecules
 chemical makeup of drug
 amount given
 size of person
 amount of protein in blood
 drug’s ability to pass through tissue’s cell
membrane
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Slide 21
Distribution (cont’d.)
Barriers to drug distribution:
 Blood-brain barrier (water-soluble electrolytes
cannot cross, but fat-soluble substances can)
 Placental barrier (allows water and fat-soluble
substances to cross)
 Selective distribution (drugs are attracted to
specific organ cells)
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Slide 22
Metabolism, or Biotransformation
series of chemical reactions altering a drug by
converting it into a water-soluble compound for
excretion
Modified from Leahy, JM, Kizilay, PE (1998). Foundations of
nursing practice. Philadelphia: Saunders.
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Slide 23
Metabolism, or Biotransformation
(cont’d.)
Factors affecting drug metabolism:
 condition of liver
 first-pass effect—rapid inactivation of some
oral medications by the liver
 age of patient
 drug half-life—time in which half the available
drug is metabolized by the body for excretion
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Slide 24
Excretion or Elimination
occurs through respiration, perspiration,
urination, or defecation
Modified from Leahy, JM, Kizilay, PE (1998). Foundations of nursing practice. Philadelphia:
Saunders.
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Slide 25
Excretion or Elimination (cont’d.)
Factors affecting rate of excretion:
 chemical composition of drug
 rate of metabolism
 administration route
 condition of excreting organs


good renal function essential
milk glands also excrete some medications

Nursing mothers should check with physician
before taking any medication.
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Slide 26
Review of Pharmacokinetics

Drug Administration


Absorption


Transported to body areas via circulating fluids
Metabolism


Absorbed and transported to site of action
Distribution


Routes – enteral, parenteral, percutaneous
Medication altered to be used by the body
Excretion

Unused medication removed from body
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Slide 27
Pharmacodynamics—Action of
Drugs in the Body
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


Drug action: physiological change occurring
in the body in response to the drug.
Drugs cannot give body organs and tissues
new functions.
Drugs can slow down or speed up cell
processes.
Drugs can replace natural substances,
protect body from foreign materials, and
inhibit cell growth.
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Slide 28
Pharmacodynamics—Action of
Drugs in the Body (cont’d.)
Four major effects:
 depression: lessens body activity
 stimulation: increases body activity
 irritation: produces areas of inflammation
 demulcence: produces soothing effect
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Slide 29
Pharmacodynamics—Action of
Drugs in the Body (cont’d.)
Additional effects:
 synergism: two drugs taken together boost
each other’s effect.
 antagonism: one drug counteracts or
reduces the effect of another drug when
taken together.
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Slide 30
Pharmacotherapeutics—Effects of
Drugs on Disease
Five categories of reasons to prescribe
medications:
 curative: cure disease
 palliative: relieve symptoms
 preventative: prevent disease
 diagnostic: diagnose conditions
 substitutive: replace natural body substances
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Slide 31
Pharmacotherapeutics—Effects of
Drugs on Disease (cont’d.)
Effects of drugs:
 desired effect: intended response to a
medication
 side effect: mild, annoying, undesirable
response to a medication
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Slide 32
Sites of Action

Local Action


Systemic Action


Drug action is limited to the site of administration
or surrounding tissues
Drug action is felt throughout the body
Remote Action

Drug action is at site distant from the site of
administration
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Slide 33
Toxicology—Poisonous Effects of
Drugs



All drugs taken in excess act as poisons.
Medication dose can mean the difference
between therapeutic effect and toxic effect.
Antidotes can be given to reverse overdose
symptoms or stop toxic effects.
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Slide 34
Toxicology—Poisonous Effects of
Drugs (cont’d.)
Unwanted effects of drugs:
 adverse reaction: unintended, undesirable,
often unpredictable effects causing unwanted
symptoms
 allergic reaction: hypersensitivity to a drug,
often after just one dose
 hypersensitivity reaction: cell-mediated
allergic reaction
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Slide 35
Toxicology—Poisonous Effects of
Drugs (cont’d.)
Anaphylaxis:
 severe, potentially fatal, allergic response
 occurs a short time after the drug is
administered
 symptoms include:





hives
reddened skin
bronchospasm
blood pressure
changes
diaphoresis



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

cyanosis
dyspnea
vascular collapse
loss of consciousness
cardiac arrhythmias
cardiac arrest
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Slide 36
Chapter 2
Lesson 2.2
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Slide 37
Undesirable Effects

Identifying undesirable
effects




Did the patient follow
instructions accurately
When did the symptoms first
occur? How long after the first
use of the drug?
Has the patient started anything
else new or changed
something? Has a new
household product been used?
If the drug was discontinued,
did the signs and symptoms
disappear?
90
80
70
60
50
East
West
North
40
30
20
10
0
1st Qtr
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2nd Qtr 3rd Qtr
4th Qtr
Slide 38
Undesirable Effects (cont’d.)




If the drug was restarted did the same effects
occur?
Could the illness cause the symptoms? Are the
signs and symptoms consistent with the
diagnosis?
Could other drug or products that are being used
concurrently cause the reaction?
Is there a possibility of a drug-drug or drug-food
interaction?
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Slide 39
Undesirable Effects (cont’d.)



Allied health professional important in
evaluating undesirable effects
Patient education should include early
identification of possible unwanted reactions
Evaluate medications on an individualized
basis
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Slide 40
Drugs and Receptor Sites
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


Drugs attach to appropriate receptor sites
Drug molecules travel in the blood until they
reach and attach to receptor site
The better the fit of the drug to the receptor
site, the better is the expected response
Drugs may be used to prevent other
chemicals from attaching to a receptor site
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Slide 41
Drugs at Receptor Sites
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Slide 42
Agonists vs Antagonists vs
Synergism

Agonist – drug that mimics body function



May compete with previously bound drugs
Synergist – One drug potentiates another
drug
Antagonist – drug that binds to a receptor
site and does not activate the site


Prevents the activation of the receptor site by the
agonist
Counteract the expected effects of other drugs
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Slide 43
Drug-Drug Interactions




Potentiation – One drug prolongs or
augments the effects of another
Tolerance – Long-term use of drug lessens
the expected effect
Summation – Two drugs are given together
and each drug has the expected effect
Cumulation (accumulation) – Drug is not
excreted as expected and it accumulates in
the body

See Table 2-8
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Slide 44
Food-Drug Interactions



Foods may react with drugs to induce toxic
effects or cause failure of therapy
Absorption may be decreased by food in the
stomach
Some medications must be taken with food to
prevent gastric irritation

See Box 2-4
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Slide 45

Yvette, a new patient, has been diagnosed by the
physician as hypertensive. The physician has
prescribed two new medications for her to take.
Yvette is also taking several other medications
for osteoarthritis and allergies; these were
prescribed by another physician, but she cannot
remember all of the names. What can you do to
make certain you have all the right information
about Yvette’s new medications so that they will
not cause any adverse or toxic reactions?
Elsevier items and derived items © 2009 by Saunders, an imprint of Elsevier Inc.
Some material was previously published.
Slide 46