Principles of Pharmacology

CHAPTER

© 2011 The McGraw-Hill Companies, Inc. All rights reserved.

50Principles of

Pharmacology


50-2

Learning Outcomes

50.1 Describe the five categories of pharmacology.

50.2 Differentiate between chemical, generic, and trade names for drugs.

50.3 Describe the major drug categories.

50.4 Identify the main sources of drug information.


50-3

Learning Outcomes (cont.)

50.5 Distinguish between over-the-counter and prescription drugs.

50.6 Compare the five schedules of controlled substances.

50.7 Describe how to register or renew a physician with the Drug Enforcement Administration (DEA) for permission to administer, dispense, and prescribe controlled drugs.


50-4

Learning Outcomes (cont.)

50.8 Carry out the procedure for renewing medications using a telephone.

50.9 Describe how vaccines work in the immune system.

50.10 Organize patient education topics related to the use of nonprescription and prescription drugs.


50-5

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


50-6

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


50-7

Medical Assistant’s Role in Pharmacology (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


50-8

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


50-9

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


50-10

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


50-11

Sources of Drugs

• Natural products– Plants – Animals– Minerals– Bacteria and fungi

• Chemical development of natural products– Synthesis of chemical makeup of a drug– Manipulation of genetic information

Foxglove – source of digitoxin


50-12

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.


50-13


2. Matching:

___ Study of poisons A. Pharmacokinetics

___ Study of what the body does to drugs B. Pharmacognosy

___ Used to prevent, diagnose, or treat disease C. Toxicology

___ Study of what drugs do to the body D.Pharmacotherapeutics

___ Study of how drugs are used to treat disease E. Pharmacodynamics

___ Study of characteristics of natural drug F. Drugs and their sources

ANSWER:

F

E

D

C

B

A


50-14

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


50-15

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


50-16

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


50-17


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 Good!


50-18

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


50-19

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


50-20


• 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


50-21


• 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


50-22

Kinds of Drug Therapy• Acute – improve a life-

threatening or serious condition

• Empiric – given before test results are available

• Maintenance – maintain health

• Palliative – reduce severity of a condition or pain

• Prophylactic – prevent disease

• Replacement – provide chemicals a patient lacks

• Supportive – for a condition other than the primary disease

• Supplemental – avoid a deficiency


50-23

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


50-24


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.


50-25


2. Toxicology includes which of these?

A. Poisons and poisonous effects of drugs

B. Excretion of drugs

C. Adverse effects of drugs

D. Drug interactions

E. Metabolism of drugs

ANSWER:


50-26

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


50-27

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


50-28

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


50-29

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


50-30

Schedule Abuse Potential ExampleI High Heroin

II High Morphine

III Lower than II (moderate dependence)

Butabarbital

IV Lower than III (limited dependence)

Diazepam

V Lower than IV (very limited dependence)

Antidiarrheals

Controlled Substances (cont.)


50-31

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


50-32

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


50-33

Writing Prescriptions (cont.)

Prescription for a single medication


50-34


Prescription for multiple medications


50-35


• Keep prescription blanks secure

• Telephone prescriptions– Only at request of the

physician

– Follow facility policy

– Document carefully


50-36


Which of the following sources of drug information is most like the package insert?

A. AHFS B. PDR C. USP/NF D. Drug Evaluations

ANSWER:

Match

___ Contains the patient information A. Subscription

___ Name of the drug and dosage B. Signature

___ Instructions to the pharmacist C. Superscription

___ Patient instructions D. Inscription

C

D

B

A

ANSWER: Correct!


50-37

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)


50-38

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


50-39

Immunizations• Schedule for

immunizations for children up to age 16 years

• Pre-exposure immunizations

• Post-exposure immunizations – antiserum or antitoxin that contains antibodies


50-40

Immunizations (cont.)

• Medical assistant should be familiar with– Indications– Contraindications– Dosages – Administration routes– Potential adverse effects– Methods of storing and

handling


50-41


ANSWER: Vaccines are administered to a person to produce reduced sensitivity to or increase immunity to an infectious disease.

Why are vaccines given to patients?


50-42

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


50-43

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


50-44

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


50-45


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!


50-46

In Summary

50.1 The five categories of pharmacology include pharmacognosy, pharmacokinetics, pharmacodynamics, pharmacotherapeutics, and toxicology.

50.2 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.


50-47

In Summary (cont.)

50.3 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 50-2.

50.4 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.


50-48

In Summary (cont.)

50.5 Nonprescription or over-the-counter drugs can be obtained without a physician’s order. For prescription drugs, patients must have a physician’s order.

50.6 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.


50-49

In Summary (cont.)

50.7 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.

50.8 Receiving and telephoning medication refills is frequently done by the medical assistant for all medications except schedule II and III drugs.


50-50

In Summary (cont.)

50.9 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.

50.10 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.


50-51

End of Chapter 50

It is easy to get a thousand prescriptions but hard to get one single remedy.

~Chinese Proverb

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Principles of Pharmacology