Download Chapter 10 Pharmacology

Chapter 10
Pharmacology
Health Care
Science
Technology
Copyright © The McGraw-Hill Companies, Inc.
Objectives
Describe where drugs come
from.
 Discuss the mechanism of
action of drugs.
 Explain how drugs are grouped
into therapeutic classes.

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Chapter 10
Objectives (cont.)
Compare the advantages and
disadvantages of different
routes of drug administration.
 Describe the four major
processes of pharmacokinetics.

3
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Objectives (cont.)
Convert units within and among
the metric, household, and
avoirdupois systems.
 Calculate basic medication
dosages.

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Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Introduction to Pharmacology 10-1
Sources of Drugs
 Pharmacotherapeutics

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Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Sources of Drugs

Natural Sources
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Pharmacognosy is the study of drugs made
from natural sources, such as plants and
animals.
Plants were the main source of medicine
until the early 1900s, when Sir F. G. Banting
and Charles Herbert Best extracted insulin
from a pancreas and tested it on diabetic
dogs.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Sources of Drugs (cont.)

Natural Sources (cont.)
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Problems associated with naturally occurring
drugs:
 Some are broken down very quickly by the
body.
 Some are poorly absorbed into the
bloodstream.
 Isolating a drug from a plant or animal can be
slow, expensive, and may result in harmful
impurities in the drug.
 Naturally occurring products can be
extremely scarce.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Sources of Drugs (cont.)

Microscopic Organisms
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8
Penicillin, isolated by Sir Alexander
Fleming in 1928, was one of the first
drugs that did not come from a plant
or animal.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Sources of Drugs (cont.)

Synthetics and Bioengineering
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Medicinal chemistry modifies natural
products by producing them synthetically
or by creating new products.
Aspirin, synthetically produced today, was
once an extract of willow bark.
Insulin was the first drug to be produced
from genetically altered bacteria.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Sources of Drugs (cont.)

Natural Sources (cont.)
–
Genetically modified E-coli used to make insulin
Plasmid
containing
human
insulin gene
Bacterial
Chromosome
10
Cell A
Cell B
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Plasmid has been
inserted into the
bacterial cell
Chapter 10
Pharmacotherapeutics

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Examines the mechanism of action
(MOA) of drugs.
Describes the effects produced by a
drug.
Determines what dose of a drug is
needed to produce a desired effect.
Determines what dose of a drug
produces toxic effects.
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Chapter 10
Pharmacotherapeutics (cont.)

12
Mechanisms of Action (MOA)
– Drugs with the same MOA are said to belong
to the same therapeutic class.
– Binding occurs when a drug combines with a
chemical in the body.
– Four common MOAs.
– MOA operates on a “lock and key” principle.
The drug is considered the key and the body
chemical the lock.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Pharmacotherapeutics (cont.)

Mechanisms of Action (cont.)
– Binding to and Stimulating a Receptor in the
Body
 Receptors – proteins found in cells.
Click for Picture
13
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Chapter 10
Pharmacotherapeutics (cont.)

Mechanisms of Action (cont.)
– Binding to and Blocking a Receptor in the Body
 Some drugs, called antagonists or blockers,
bind to a receptor without causing a response,
thus preventing the naturally occurring key
from binding.
Click for Picture
15
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Pharmacotherapeutics (cont.)

Mechanisms of Action (cont.)
– Inhibiting an Enzyme
 Enzyme inhibitors increase or decrease the
concentration of an enzyme.
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Chapter 10
Pharmacotherapeutics (cont.)

Mechanisms of Action (cont.)
– Decreasing the Movement of a Chemical
Across a Cell Membrane
 Pumps and channels are used by cell
membranes to control the movement of
chemicals into and out of a cell.
 Pumps can be inhibited and channels can
be blocked by this type of drug.
Click for Picture
19
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Chapter 10
Pharmacotherapeutics (cont.)

A side effect is any effect produced by
a drug that is not the desired effect.
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21
Local Side Effects
 Occur before a drug is absorbed into
the bloodstream.
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Chapter 10
Pharmacotherapeutics (cont.)
–
22
Systemic Side Effects
 Take place after being absorbed into
the bloodstream.
 May take the form of an allergic
reaction, since drugs are not a
“natural” part of our body.
 Most occur because the drug affects
cells other than the target cells.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Section 10-1
Apply Your Knowledge
Where do drugs come from?
Answer:
1. Natural sources such as plants and animals.
2. Microscopic organisms such as bacteria,
fungi, and molds.
3. Synthetics and bioengineering.
23
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Chapter 10
Classes of Drugs and
Routes of Administration 10-2
Therapeutic Classes of Drugs
 Routes of Administration

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Chapter 10
Therapeutic Classes of Drugs

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Drugs in a therapeutic class produce
their effect in the same way.
Examples are listed on the following
slides.
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Chapter 10
Therapeutic Classes of Drugs (cont.)
 Angiotensin Converting Enzyme Inhibitors
– Angiotensin is a naturally occurring protein in
the body. An enzyme called angiotension
converting enzyme (ACE) activates angiotensin,
which, when overactive, causes high blood
pressure, or hypertension.
– ACE inhibitors reduce the production of
angiotensin.
– Representative drugs: Accupril®, Lotensin®,
Prinivil®, Vasotec®, and Zestril®.
– Common side effects include headache and
dizziness.
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Chapter 10
Therapeutic Classes of Drugs (cont.)
 Beta-1 Blockers
– Bind to beta-1 receptors without stimulating
them, preventing epinephrine (adrenalin)
and norepinephrine from binding.
– Representative drugs: Lopressor®,
Tenormin®, Toprol®.
– Indications: hypertension, tachycardia or
rapid heartbeat.
– Common side effects: dizziness,
drowsiness.
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Chapter 10
Therapeutic Classes of Drugs (cont.)
 Beta-2 Agonists
– These drugs bind to beta-2
receptors on the smooth
muscle cells of the
bronchioles, causing
dilation. Representative
drugs: Ventolin®, Proventil®,
Serevent®, Alupent®,
Brethine®.
– Indications: asthma,
emphysema.
– Common side effects:
tremors, increased heart
rate, and insomnia.
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Chapter 10
Therapeutic Classes of Drugs (cont.)
 Antihistamines
– Antihistamines bind to histamine
receptors, without stimulating them.
– Representative drugs: Allegra®,
Benadryl®, Claritin®, Zyrtec®.
– Indications: itching, nasal
congestion, seasonal allergies such
as hay fever.
– Common side effects: dry mouth and
drowsiness.
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Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Therapeutic Classes of Drugs (cont.)
 H2 Antagonists
– Bind to H2 receptors, found
only in the stomach, to
decrease the amount of
hydrochloric acid produced.
– Representative drugs:
Tagamet®, Pepcid®, Zantac®.
– Indications: gastroesophageal
reflux disorder, gastric ulcers,
duodenal ulcers.
– Common side effects:
diarrhea, headache.
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Chapter 10
Therapeutic Classes of Drugs (cont.)
 Proton Pump Inhibitors
– Drugs that turn off the proton pumps in the stomach,
which reduces stomach acid.
– Representative drugs: Prilosec®.
– Indications: gastroesophageal reflux disorder,
gastric ulcers, duodenal ulcers.
– Common side effects: diarrhea, headache.
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Chapter 10
Therapeutic Classes of Drugs (cont.)
 Narcotic Analgesics
– Drugs that bind to and stimulate the endorphin
receptors in the spine which inhibit nerve cells that
carry pain to the brain.
– Representative drugs: morphine, codeine,
Demerol®, Vicodin®, Percodan®.
– Indications: severe pain.
– Common side effects: drowsiness, slow and
shallow breathing, constipation.
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Chapter 10
Therapeutic Classes of Drugs (cont.)
 Nonsteroidal Anti-inflammatory Drugs
– Nonsteroidal anti-inflammatory drugs (NSAIDS)
inhibit the enzyme prostaglandin synthase, which
makes prostaglandins.
– Representative drugs: aspirin, Motrin®, Advil®,
Relafen®, Naprosyn®, Aleve®.
– Indications: mild to moderate pain, inflammation,
fever.
– Common side effects: stomach irritation.
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Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Therapeutic Classes of Drugs (cont.)
 Reverse Transcriptase Inhibitors
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Inhibit the activity of the enzyme reverse
transcriptase, which is needed to convert RNA to
DNA.
Representative drugs: AZT, Combivir®, Sustiva®,
Retrovir®.
Indications: HIV infection.
Common side effects: anemia, fever, rash, headache,
lack of energy, nausea, vomiting, diarrhea, stomach
pain, cough, shortness of breath, sore throat.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Therapeutic Classes of Drugs (cont.)
 Statins
– Drugs that inhibit the enzyme HMG CoA
reductase.
– Representative drugs: Lipitor®, Pravachol®,
Zocor®.
– Common side effects: nausea, vomiting,
diarrhea, and liver damage.
35
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Chapter 10
Routes of Administration
Routes of Administration (ROA) – the
different ways used to get a drug
into the tissues of the body.
36
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Chapter 10
Routes of Administration (cont.)

Oral Administration
–
–
37
The most common route. Client
swallows a tablet, capsule, or liquid.
Usually requires 30 to 60 minutes
before producing an effect, or onset of
action.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Routes of Administration (cont.)

Parenteral Administration –
all forms of administration,
other than oral.
– Metered-Dose Inhaler
 Delivers medications
directly to the lungs.
 Rapid action.
 Minimal systemic side
effects.
38
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Chapter 10
Routes of Administration (cont.)
–
39
Transdermal Patch – one
of the most consistent
and convenient dosage
forms.
 Remove and discard
old patch.
 Select a site for new
patch.
 Apply the patch.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Routes of Administration (cont.)
–
40
Injections – used when a rapid effect is needed.
 Subcutaneous (SC) injection – most
frequently given in the upper arm, front of
thigh, or abdomen.
 Intramuscular (IM) injection – normally given
into relatively large muscles of the shoulder,
buttocks, or outer portions of the thigh.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Section 10-2
Apply Your Knowledge
What is the largest volume that can be
given with an SC injection?
Answer:
The largest volume is 1 milliliter (mL).
41
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Chapter 10
Pharmacokinetics and Dosages 10-3


42
Pharmacokinetics
Dosages
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Pharmacokinetics
Pharmacokinetics is
the study of the
four processes
that affect the
plasma
concentration of
drugs.
43
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Chapter 10
Pharmacokinetics (cont.)

Absorption – the process by which a
drug enters the plasma.
–
44
Oral medications are dissolved in the
stomach.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Pharmacokinetics (cont.)

Distribution – where the drug goes
after entering the plasma.
–
45
Some of the drug binds to the proteins
in the plasma; some diffuses into other
tissues.
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Chapter 10
Pharmacokinetics (cont.)


46
Transformation – chemical changes in
a drug that occur after it has been
absorbed into the body.
Elimination – the process that
removes a drug from the body.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Dosages
Dosages are usually based on
the weight of an individual.
47
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Chapter 10
Dosages (cont.)

Effects of Individual Differences on
Maintenance Doses
–
48
Age, body fat, and diseases that affect
the liver and kidneys may require
altering the dosage of a drug.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Section 10-3
Apply Your Knowledge
List the 4 processes of
pharmacokinetics.
Answer:
1. Absorption
2. Distribution
3. Transformation
4. Elimination
49
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Chapter 10
Systems of Measure 10-4



50
The Metric System
Other Systems of Measure
Basic Dosage Calculations
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
The Metric System

The metric system is the most widely
used measurement system in
pharmacy.
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–
51
Dosage of a drug is usually measured in
milligrams (mg).
Liquid drugs are often measured in
milliliters (mL).
Client’s body weight may be measured in
kilograms (kg).
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Other Systems of Measure



52
Household system – uses teaspoon
and tablespoon.
Avoirdupois system – uses
measurements such as fluid ounce
and pound.
Apothecary system – seldom used, it
includes terms such as minim and
grain.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Other Systems of Measure (cont.)

53
Converting from
one system to
another with
factors:
– 1 kg = 2.2 lb
– 1 fl oz = 30 mL
– 1 tsp = 5 mL

Example:
25 kg = ? lb
25 kg = 1 kg
? lb
2.2 lb
25 X 2.2 = 1 X ?
Copyright © The McGraw-Hill Companies, Inc.
? = 55 lb
Chapter 10
Basic Dosage Calculations

A physician’s order must be obtained to
administer a dose. It must include:
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–
–
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54
The name of the drug.
The amount of drug prescribed.
The frequency with which it should be
administered.
The route of administration.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Basic Dosage Calculations (cont.)

A simple way to calculate doses is to
use the following proportion:
Known unit on hand
Known dosage form
55
_______Dose ordered______
Unknown amount to be given
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Basic Dosage Calculations (cont.)
–
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–
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56
Known unit on hand – the amount of grams or
milligrams in a particular drug for which the
dosage is known.
Known dosage form – a typical amount of
medicine for which you are given the gram or
milligram equivalents.
Dose ordered – the amount of grams or
milligrams ordered.
Unknown amount to be given – what you are
trying to determine; the amount of medicine to
be given.
Copyright © The McGraw-Hill Companies, Inc.
Chapter 10
Section 10-4
Apply Your Knowledge #1
Convert 25 grams to milligrams.
Answer:
1. Add a decimal point to the measurement: 25. g
2. Add 3 zeroes so you can move the decimal point three
places to the right: 25.000 g
3. Move the decimal point to the right three places:
25,000
4. Change the unit: 25,000 mg
57
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Chapter 10
Section 10-4
Apply Your Knowledge #2
Calculate the dose to give for
500 mg Augmentin®.
Answer:
20 mL
58
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Chapter 10
Chapter 10 Credits
Slide 28
Slide 30
Slide 31
Slide 32
Slide 33
Slide 38
Slide 39
Slide 58
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Glaxo Wellcome, Inc.
Glaxo Wellcome, Inc.
Astra
Roxane
McNeil-PPC, Inc.
Aaron Haupt
Medical Images
SmithKline Beecham
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Chapter 10