1.
Introduction to
Pharmacology Course
Ms. Maria Jose Baňaga
Villafuerte
R.N. M.A.N.
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2.
Objectives
• Define the common terms related to Pharmacology.
• Explain how drugs are named.
• Explain the concepts of drugs in terms of pharmacokinetics,
pharmacodynamics and pharmacotherapeutics.
• Identify the common drug interactions.
• Identify the common patient variables affecting drug action.
• List the various routes of administration and the role of
nurses in drug administration.
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3.
Definition of Pharmacology
• is the study of drugs and its origin,
chemical structure, preparation,
administration, action, metabolism and
excretion.
• The study of drugs that alter
functions of living organisms.
3

4.
Implication of Pharmacology
to Nursing
– Responsible for drug administration
– Responsible for the administration of
medications that they direct others to give.
– Ethical and legal responsibilities
4

5.
Basic Concepts of
Pharmacology
• Drugs
– are chemicals that
alter
physiochemical
processes in body
cells.
– They can stimulate
or inhibit normal
cellular functions.
– Used
interchangeably with
medicines.
5

6.
Drug Names
1. Generic or Nonproprietary Name:
name approved by the Medical or Pharmaceutical
Associations in the original country of
manufacture and is adopted by all countries.
e.g. Paracetamol
2. Brand name or trade name:
name given by the manufacturer of the drug
e.g. Adol or Panadol
3. Chemical name
name that describes the atomic or chemical
strucuture
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7.
Drug Names
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8.
Example
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9.
Exercise 1: Reading the Label
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10.
PharmacokineticsPharmacokinetics
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11.
Pharmacokinetics-activities
within the body
• It includes:
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12.
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13.
AbsorptionAbsorption
• Involves the way a drug enters the body and
passes into the fluids and tissues.
– Passive transport
– Active transport
– Pinocytosis
• Rate of Absorption:
– Drug Solubility –
• water soluble drugs
• lipodystrophy
– Route of Administration – IV, IM, SC, Oral
– Degree of blood flow
through the tissues 13

14.
Factors affecting
Absorption
Factors affecting
Absorption
– Drug Solubility –
• water soluble drugs
• lipodystrophy
– Bioavailability- the extent to which active ingredients
are absorbed and transported to sites of action.
– pH
– Drug concentration
– Circulation to site of absorption
– Absorbing surface
– Route of administration
– Presence of body conditions
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15.
DistributionDistribution
• Is defined as the way the drug moves from the
circulating body fluids to its site of action.
Note: The greater the blood supply in a body organ,
the faster the medication is absorbed
– Therapeutic effect – certain blood level is
maintained for the drugs to be effective.
– Toxic effect - when blood level increase
significantly over the therapeutic level.
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16.
Bioavailability
• is defined as the extent to which active ingredients are
absorbed and transported to sites of action.
• Factors
1. Drug solubility
2. Pharmaceutical formulation
3. pH
4. Food
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17.
Metabolism or
Biotransformation
Metabolism or
Biotransformation
• is defined as the process by which drug is
converted by the liver to inactive compounds
through a series of chemical reactions.
– Plasma, kidneys and membranes of intestines.
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18.
ExcretionExcretion
• Is the elimination of drugs from the
body
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19.
Half-lifeHalf-life
• Refers to the time required for the body to eliminate 50% of
the drug.
– It is important in planning the frequency of dosing.
• Short half-life (2-4 hours) : needs to be given frequently
• Long half life: (21-24 hours): requires less frequent dosing
Note: It takes 5 to 6 half lives to eliminate approximately 98% of a drug from
the body
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20.
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21.
• Liver and kidney disease patients may have
problems of excreting a drug.
• Difficulty in excreting a drug increases the half-life
and increases the risk of toxicity.
• Implication: may require frequent diagnostic tests
and measuring renal and hepatic function.
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Half-lifeHalf-life

22.
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PharmacodynamicsPharmacodynamics

23.
PHARMACODYNAMICS
• Is the study of biochemical, and
physiological and effect of drugs.
• “what the drug does to the body”
– Primary Effects - drug’s desired or
therapeutic effect
– Secondary Effects – all other effects
whether desirable or undesirable.
24

24.
Drug Attachment
• Medication chemically
binds to specific sites
called “receptor sites”
– Agonist-chemical fits at
receptor site well
– Antagonist- a chemical blocks
another chemical from getting to
a receptor
– Partial agonist - attach to the
receptor but only produce a
small effect
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25.
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26.
Basics of Drug Action
• Desired action – the expected response of a
medication
• Side effects –known and frequently
experienced, expected reaction to drug.
• Adverse reaction –unexpected,
unpredictable reactions that are not related
too usual effects of a normal dose of the
drug. 27

27.
Drug Interaction
• Takes place when one drug alters the
action of another drug.
• Some are helpful but often produce
adverse effects.
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28.
Common Drug Interactions
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• Additive effect- takes place when 2 drugs
are given together & double the effect is
produced.
Alcohol + aspirin= Pain relief

29.
• Antagonistic effect- takes place when 1
drug interferes with the action of another
drug.
– Protamine sulphate to counteract heparin
toxicity
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Common Drug Interactions

30.
• Displacement effect - takes place
when 1 drug replaces another at the
drug receptor site, increasing the
effect of the 1st
drug.
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Common Drug Interactions

31.
• Incompatibility –occurs when 2 drugs
mixed together in a syringe produce a
chemical reaction so they cannot be
given.
e.g. Protamine sulfate & vitamin K
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Common Drug Interactions

32.
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• Interference- occurs when 1 drug promotes
the rapid excretion of another, thus reducing
the activity of the 1st
.
• Synergistic effect takes place when the
effect of 2 drugs taken at the same time is
greater than the sum of each drug given
alone.
E.g. combining diuretics & adrenergic
blockers to lower the BP
Common Drug Interactions

33.
09/19/13 Pharmacology Unit 1 Class
Session 1Pharmacology
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34.
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PharmacotherapeuticsPharmacotherapeutics

35.
Pharmacotherapeutics
• Is defined as the use of drugs to treat
diseases.
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
 Depends on:
 Severity
 Urgency
 Prognosis of patient’s condition

36.
Routes of Drug
Administration

37.
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1: Enteral Medications
• administered directly into the G.I.T.
through the oral, nasogastric (NG) or
rectal routes
Advantages:
Convenience for nurse & patient
Most medications are available in oral route
Inexpensive to make oral preparations
Can be removed by gastric lavage or make
to vomit

38.
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Disadvantages
• cannot be administered to very
nauseated/vomiting or
unconscious persons
• some loose their effectiveness if
mixed with gastric secretions
• onset of action may vary due to
changes in absorption in the GIT

39.
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Forms of Oral Medication
• Capsules-are gelatin containers that hold
powder or liquid medicine.
• Elixirs- clear liquids made up of drugs dissolved
in alcohol & water with coloring & flavoring
agents added.
• Emulsions-are solutions that have small
droplets of water & medication dispersed in oil,
or oil & medication dispersed in water.

40.
• Lozenges- are medicines mixed with a
hard sugar base to produce a small,
hard preparation of various shapes &
sizes.
• Suspensions- are liquids w/ solid,
insoluble drug particles dispersed
throughout.
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Forms of Oral Medication

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Session 1Pharmacology
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Forms of Oral Medication
• Syrups-are liquids w/ a high sugar content
designed to disguise the bitter taste of a
drug. Pediatric use.
• Tablets-dried, powdered drugs compressed
into small shapes.

42.
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2.Parenteral Administration
• Reasons:
1. When the patient cannot take an oral
medication
2. When the medication must be given quickly
3. When medication might be destroyed by
gastric enzymes
4. When medication must be given at a
controlled rate
5. When the medication is not available in an
enteral form.

43.
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• INTRAMUSCULAR – 90 °
– Provides faster medication absorption
because of muscle’s greater vascularity
• SUBCUTANEOUS- 45 °
– Placing medications in the loose connective
tissue under the dermis
• INTRADERMAL- 15 °
Parenteral Medications

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Other Routes of
Administration
• Topical administration – skin
– Cleanse
– Soften
– Disinfect
– Lubricate
– E.g. clotrimazole –cream
dermatophytosis
– atropine- eye-dilate the pupil
• Transdermal route -
nitroglycerin (skin patch) systemic
vasodilation in angina

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Other Routes of
Administration
• Inhalation – provides rapid delivery of
drugs to a large area of mucus
membranes & tissues of the respiratory
system.
– Anesthesia
– Bronchodilators
• Intranasal – desmopressin for diabetes
insipidus
– Calcitonin- a peptide hormone for tx of
osteoporosis

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• Intrathecal injection- introduction of hypodermic
needle into the subarachnoid space for the purpose
of instilling a material for diffusion throughout the
spinal fluid.
• Intraventricular- space into the ventricle
– Both gains access to the CSF e.g. amphotericin B
–in meningitis
Other Routes of
Administration

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48.
Ms. Maria Jose

49.
First-Pass Effect
• Drugs taken orally are absorbed from the small
intestine directly into the portal venous system. The
portal veins deliver these absorbed molecules into
the liver, which immediately transforms most of the
chemicals delivered to it by a series of liver
enzymes.
active
metabolites
Inactive (excreted)

50.
Protein Binding
• Most drugs are bound to some extent to
proteins in the blood to be carried into
circulation.
• The protein-drug complex is relatively
large & cannot enter into capillaries & then
into tissues to react. The drug must be freed
from the protein’s binding site at the tissues.

51.
• Tightly bound – released very slowly. these
drugs have very long duration of action (not
freed to be broken down or excreted) , slowly
released into the reactive tissue.
• Loosely bound – tend to act quickly and
excreted quickly
• Compete for protein binding sites – alters
effectiveness or causing toxicity when 2 drugs
are given together.
Protein Binding

52.
Half-Life
• Half life of a drug is the time it takes for the
amount of drug in the body to decrease to one-
half of the peak level it previously achieved.
• e.g.
– 20 mg of a drug with half-life of 2 hours, 10 mg of the
drug will remain 2 hours after administration. Two
hours later, 5 mg will be left (one-half of the previous
level); in 2 more hours, only 2.5 mg will remain.

53.
Why to know half-life?
– To determine the appropriate timing for a
drug dose or
– determining the duration of a drug’s effect
on the body.

54.
Determining the Impact of
Half-Life on Drug Levels
• A patient is taking a drug that has a half-
life of 12 hours. You are trying to
determine when a 50-mg dose of the drug
will be gone from the body.
– In 12 hours, half of the 50 mg (25 mg) would be in
the body
– In another 12 hours (24 hours) half of 25 mg (12.5
mg) would remain in the body.

55.
– After 36 hours, half of 12.5 mg (6.25 mg)
would remain
– After 48 hours, half of the 6.25 mg
(3.125 mg) would remain
– After 60 hours, half of the 3.125 mg
(1.56 mg) would remain
– After 72 hours, half of the 1.56 mg (0.78
mg) would remain
Determining the Impact of
Half-Life on Drug Levels

56.
– After 84 hours, half of the 0.78 mg (0.39
mg) would remain
– Twelve more hours (for a total of 96
hours) would reduce the drug amount
to 0.195 mg
– Finally,12 more hours (108 hours)
would reduce the amount of the drug
into the body to 0.097 mg, which is
negligible
– Therefore, it would take 4 ½ to 5 days to
clear the drug from the body.
Determining the Impact of
Half-Life on Drug Levels