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Principles of Pharmacology - McGraw Hill Higher Education
CHAPTER
19
Principles of
Pharmacology
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-2
Learning Outcomes
19.1 Describe the five categories of
pharmacology.
19.2 Differentiate between chemical, generic, and
trade names for drugs.
19.3 Describe the major drug categories.
19.4 Identify the main sources of drug information.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-3
Learning Outcomes (cont.)
19.5 Distinguish between over-the-counter
and prescription drugs.
19.6 Compare the five schedules of
controlled substances.
19.7 Describe how to register or renew a
physician with the Drug Enforcement
Administration (DEA) for permission to
administer, dispense, and prescribe
controlled drugs.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-4
Learning Outcomes (cont.)
19.8 Carry out the procedure for renewing
medications using a telephone.
19.9 Describe how vaccines work in the immune
system.
19.10 Organize patient education topics related to
the use of nonprescription and prescription
drugs.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-5
Introduction
• Pharmacology – science or study of
drugs
• Medication errors can result in injury or
death
• Medical assistant
– Knowledge of the foundations of
pharmacology
– Understand role of drugs in ambulatory
medical facilities
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-6
Medical Assistant’s Role in
Pharmacology
• Prescription drugs –
physician’s order
required to dispense
and administer
• OTC drugs –
purchased by patient
for self-treatment
• You should
– Be sure the physician
is aware of all
medications the
patient is taking
– Ask patients about use
of alcohol and
recreational drugs
– Provide patient
education
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
Medical Assistant’s Role in Pharmacology
19-7
(cont.)
• Administration of drugs
– Check state regulations
scope of practice
– Understand pharmacologic principles
– Translate prescriptions
– Answer basic patient questions
– Adhere to legal requirements
– Keep accurate records
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-8
Drugs and Pharmacology
• Drug – chemical compound used to
prevent, diagnose, or treat disease
• Pharmacognosy – study of
characteristics of natural drugs and their
sources
• Pharmacodynamics – study of what
drugs do to the body
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-9
Drugs and Pharmacology (cont.)
• Pharmacokinetics – study of what the
body does to drugs
• Pharmacotherapeutics – study of how
drugs are used to treat disease
• Toxicology – study of poisons or
poisonous effects of drugs
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-10
Drugs and Pharmacology (cont.)
• Prescribe – physician gives a patient a
prescription to be filled by a pharmacist
• Administer – give a drug by injection,
mouth, or other route that introduces it into
the body
• Dispense – health-care professional
distributes the drug, in a properly labeled
container, to the patient for whom it is
prescribed
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-11
Sources of Drugs
• Natural products
– Plants
– Animals
– Minerals
– Bacteria and fungi
Foxglove – source of
digitoxin
• Chemical development of natural products
– Synthesis of chemical makeup of a drug
– Manipulation of genetic information
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-12
Apply Your Knowledge
1.
What is the role of the medical assistant in
pharmacology?
ANSWER: The medical assistant should be sure the
physician is aware of all medications the patient is
taking, including OTC medications; ask patients about
use of alcohol and recreational drugs; and provide
patient education. If the scope of practice permits, the
medical assistant may also be responsible for
administering some medications.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-13
Apply Your Knowledge
2.
Matching:
ANSWER:
C Study of poisons
___
A. Pharmacokinetics
A Study of what the body does to drugs
___
B. Pharmacognosy
F Used to prevent, diagnose, or treat disease
___
C. Toxicology
E Study of what drugs do to the body
___
D. Pharmacotherapeutics
D Study of how drugs are used to treat disease
___
E. Pharmacodynamics
B Study of characteristics of natural drug
___
and their sources
F. Drugs
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-14
Pharmacodynamics
• Mechanism of action
of a drug to produce a
therapeutic effect
• Interaction between
drug and target cells
and body’s response
to the interaction
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-15
Pharmacokinetics
•
What the body does to a drug
– Absorption
•
•
•
Conversion of a drug into a form the body can use
Allows the drug to enter the blood and tissues
Rate and extent of absorption depend on
– Route of administration
– Characteristics of the drug
– Distribution
•
Transportation of a drug from site of administration
to site of action
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-16
Pharmacokinetics (cont.)
– Metabolism
•
•
•
Drug molecules are transformed into
metabolites
Usually in liver, some in kidneys
Affected by age, genetic makeup, and
characteristics of drug
– Excretion
•
•
Manner in which a drug is eliminated from
the body
Most via urine
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-17
Apply Your Knowledge
What is the difference between pharmacodynamics
and pharmacokinetics?
ANSWER: Pharmacodynamics is the way a drug affects the
body to produce its effect. It is the interaction between the
drug and cells and the body's response to the interaction.
Pharmacokinetics is what the body does to the drug and
includes absorption, distribution, metabolism, and excretion
of the drug.
Very
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-18
Pharmacotherapeutics
• Clinical pharmacology
• Drug names
– Generic – official name
– International nonproprietary name
– Chemical name
– Trade – brand or proprietary name
• Generic and trade names used most often
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-19
Pharmacotherapeutics (cont.)
• Drug categories
– Action on the body
– General therapeutic
effect
– Body system affected
• Indication and labeling
– Indication – reason(s)
for using a drug
– Must be approved by
FDA to be part of
labeling
– Off-label use
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-20
Pharmacotherapeutics (cont.)
• Safety
– Adverse reaction to drug
– Interaction with another medication
– Be alert to patient complaints after starting a
new drug
• Efficacy – drug is working as expected
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-21
Pharmacotherapeutics (cont.)
• If a patient complains a drug is not working
– The patient may not understand how the drug
works
– Dosage may need to be adjusted
– Therapeutic level may not have been reached
– Wrong drug may have been prescribed
– Some drugs work better for one patient than
another
– Some forms of drugs work better
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-22
Kinds of Drug Therapy
• Acute – improve a lifethreatening or serious
condition
• Prophylactic – prevent
disease
• Empiric – given before
test results are available
• Replacement – provide
chemicals a patient lacks
• Maintenance – maintain
health
• Palliative – reduce
severity of a condition or
pain
• Supportive – for a
condition other than the
primary disease
• Supplemental – avoid a
deficiency
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-23
Toxicology
• Study of poisonous effects of drugs
– Adverse effects
– Drug interactions
• Patient education
– Inform physician of any adverse effects
– Discuss concerns with physician or
pharmacist
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-24
Apply Your Knowledge
1. Mr. Anderson is complaining that the new
medication does not seem to be working. What
may be the reason for this?
ANSWER: Mr. Anderson may not understand how the drug
works. His dosage may need to be adjusted, or the therapeutic
level may not have been reached. The wrong drug may have
been prescribed for him, or this particular drug may not work
for as well for him as for another patient. He may need the
medication in a different form.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-25
Apply Your Knowledge
2. Toxicology includes which of these?
ANSWER:
A.
B.
C.
D.
E.
Poisons and poisonous effects of drugs
Excretion of drugs
Adverse effects of drugs
Drug interactions
Metabolism of drugs
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-26
Sources of Drug Information
• Sources must be up-to-date
• PDR
– Information provided by pharmaceutical
companies
– Information closely resembles package insert
– Published annually
• Drug Evaluations – published
annually by the AMA
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-27
Sources of Drug Information
• USP/NF
– Official source of drug standards
– Published about every 5 years
• AHFS – published by the
American Society of
Hospital Pharmacists
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-28
The FDA Regulatory Function
• New drugs
– Clinical trials
• Safety
• Efficacy
• Drug manufacturing
–
–
–
–
Identity
Strength
Purity
Quality
• OTC drugs
• Prescription drugs
• Pregnancy categories
–
–
–
–
–
A
B
C
D
X
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-29
Controlled Substances
• Drugs categorized as potentially
dangerous and addictive
• Strictly regulated by federal laws
• Comprehensive Drug Abuse Prevention
and Control Act (1970)
– Created the DEA
– Strengthened drug enforcement authority
– Schedules – based on abuse potential
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-30
Controlled Substances (cont.)
Schedule
Abuse Potential
Example
I
High
Heroin
II
III
High
Lower than II
(moderate dependence)
Morphine
Butabarbital
IV
Lower than III
(limited dependence)
Diazepam
V
Lower than IV
(very limited dependence)
Antidiarrheals
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-31
Controlled Substances (cont.)
• Comprehensive Drug Abuse Prevention and
Control Act (1970)
– Controlled substance
labeling
– Doctor registration
– Ordering controlled
substances
– Drug security
– Record keeping
– Dispensing records
– Inventory records
– Disposal of drugs
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-32
Writing Prescriptions
• Parts of a prescription
– Superscription
• Patient information
•
– Inscription
• Name of the drug
• Amount of drug per dose
– Subscription –
directions to the
pharmacist
– Signature – patient
instructions
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-33
Writing Prescriptions (cont.)
Prescription for a
single medication
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-34
Writing Prescriptions (cont.)
Prescription for
multiple medications
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-35
Writing Prescriptions (cont.)
• Keep prescription
blanks secure
• Telephone
prescriptions
– Only at request of the
physician
– Follow facility policy
– Document carefully
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-36
Apply Your Knowledge
Which of the following sources of drug information is most
like the package insert? ANSWER:
A. AHFS
B. PDR
Match
ANSWER:
C. USP/NF
D. Drug Evaluations
Correct!
C Contains the patient information
___
A. Subscription
___
D Name of the drug and dosage
B. Signature
A Instructions to the pharmacist
___
C. Superscription
B Patient instructions
___
D. Inscription
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-37
Vaccines
• Special preparations made
from microorganisms
• Administered to produce
reduced sensitivity to or
increased immunity to an
infectious disease
• Body creates antibodies in
response to an antigen
(vaccine)
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-38
Antibody Formation
1. Antigen enters body
2. White cells produce antibodies
3. Antibodies combine with antigens
to neutralize them
4. This arrests or prevents reaction or disease
5. Vaccines stimulate antibody formation and
reduce symptoms if patient is exposed to
disease
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-39
Immunizations
• Schedule for
immunizations for
children up to age 16
years
• Pre-exposure
immunizations
• Post-exposure
immunizations –
antiserum or antitoxin
that contains antibodies
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-40
Immunizations (cont.)
• Medical assistant should be familiar with
– Indications
– Contraindications
– Dosages
– Administration routes
– Potential adverse effects
– Methods of storing and
handling
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-41
Apply Your Knowledge
Why are vaccines given to patients?
ANSWER: Vaccines are administered to a person to
produce reduced sensitivity to or increase immunity to
an infectious disease.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-42
Patient Instruction on Medications
• Medical assistant role is important
• OTC drugs
– Should not be used to avoid medical care
– May not produce enough therapeutic benefit
– May be dangerous in combination with other
substances or drugs
– May mask symptoms or aggravate a problem
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-43
Patient Instruction on Medications (cont.)
• Prescription drugs
– Inform patient about special
considerations and drug
safety precautions
– Encourage patient to
• Maintain a complete list
of medications
• Report adverse reactions
• Patient compliance
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-44
Patient Instruction on Medications (cont.)
• To prevent medication errors, be sure
patient understands prescription
– How and when to take the medication
– Appropriate language
– Demonstrate if necessary
– Review warnings about
the medication
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-45
Apply Your Knowledge
Mrs. Del Rosario tells you she does not take any
medication when you are taking her history. When you
question her further, she says she takes an OTC pain
medication occasionally and routinely take several herbal
supplements. What should you tell her?
ANSWER: You should tell her it is important to report all
medications, including OTC drugs and herbal and other
supplements, to the physician and that they may be
dangerous in combination with other substances or
drugs or may mask symptoms or aggravate a problem.
Nice Job!
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-46
In Summary
19.1 The five categories of pharmacology include
pharmacognosy, pharmacokinetics,
pharmacodynamics, pharmacotherapeutics, and
toxicology.
19.2 The chemical name of a drug is based upon the
chemical makeup of the medication. The generic
name is the drug’s official name, and the trade name
is the name given a medication by the manufacturer.
A medical assistant should be familiar with both the
generic and trade names.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-47
In Summary (cont.)
19.3 Drug categories are sometimes named based upon
their action; for example, anticonvulsants are used to
treat convulsions (seizures). The major drug
categories and their actions are outlined in Table 192.
19.4 The main book sources for drug information are the
Physicians’ Desk Reference (PDR), Drug
Evaluations, United States Pharmacopeia/National
Formulary, and the American Hospital Formulary
Service. You may also access medication information
from package inserts, at the web site www.rxlist.com,
or at other reliable Internet sites.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-48
In Summary (cont.)
19.5 Nonprescription or over-the-counter drugs can be
obtained without a physician’s order. For prescription
drugs, patients must have a physician’s order.
19.6 For drugs that have been classified as controlled
substances because they are potentially dangerous
and addictive, extensive regulations apply. There are
five schedules (I to V) of controlled substances, with
schedule I being the most addictive.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-49
In Summary (cont.)
19.7 All physicians must be registered with the Drug
Enforcement Administration and follow the legal
requirements of the Controlled Substances Act of
1970 to administer, dispense, and prescribe controlled
drugs. The medical assistant must follow these legal
requirements when registering the physician.
19.8 Receiving and telephoning medication refills is
frequently done by the medical assistant for all
medications except schedule II and III drugs.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-50
In Summary (cont.)
19.9 Immunizations usually contain killed or weakened
organisms. When given, they stimulate the body to
build up a resistance to the organism. They are used
to provide immunity against specific diseases.
19.10 Patients should be educated about why, when, and
how they should take medications. This includes
instruction to ensure patient compliance regarding
nonprescription and prescription drugs, herbal
remedies, and supplements. Patients should also be
instructed about the dangers of medication
combinations, the importance of reporting an adverse
effect, and maintaining a complete medication list.
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
19-51
End of Chapter 19
It is easy to get a
thousand prescriptions
but hard to get one
single remedy.
~Chinese Proverb
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
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