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PHARMACOLOGY FOR NURSESPHARMACOLOGY FOR NURSESA Pathophysiological ApproachA Pathophysiological Approach

FOURTH EDITIONFOURTH EDITION

CHAPTER

Drug Classes and Schedules

Pharmacology for Nursing: A Pathophysiology Approach, Fourth EditionMichael Patrick Adams | Leland N. Holland | Carol Urban

Drug Are Organized in Two WaysDrug Are Organized in Two Ways

• Therapeutic classification• Pharmacologic classification

Therapeutic Classification of DrugsTherapeutic Classification of Drugs

• Based on what the drug does clinically• Examples

– Anticoagulants– Antidepressants– Antineoplastics

Table 2.1 Therapeutic Classification

Pharmacologic Classification Pharmacologic Classification of Drugsof Drugs

• Based on the drug's mechanism of action, or how the drug produces its effect– At molecular, tissue, or body-system

level• More specific than therapeutic

classification

Pharmacologic Classification Pharmacologic Classification of Drugsof Drugs

• Requires understanding of biochemistry and physiology

• May be described with varying degrees of complexity

Table 2.2 Pharmacologic Classification

ExamplesExamples

• Calcium-channel blockers• Diuretics• Adrenergic antagonists

““PrototypePrototype”” Drug—Serves as Model Drug—Serves as Model for a Drug Classfor a Drug Class

• Is well understood• Has known action and adverse effects• Is used to compare other drugs in the

same pharmacologic class• May not be the most widely used drug

in its class• Disagreements may exist over which

drug should serve as prototype drug.

Newer Drugs in the Same ClassNewer Drugs in the Same Class

• Newer drugs in the same class may have replaced the prototype drug's use because they:– Are more effective– Have a more favorable safety profile– Have longer duration of action

Most Drugs Have Three NamesMost Drugs Have Three Names

• Chemical• Generic • Trade

Drug Has One Chemical NameDrug Has One Chemical Name

• Assigned using standard nomenclature established by International Union of Pure and Applied Chemistry (IUPAC)

• Describes physical and chemical properties of drug

• Sometimes helpful in predicting a substance's physical and chemical properties

Drug Has One Chemical NameDrug Has One Chemical Name

• Complicated, difficult to remember and pronounce– Example: chemical name for diazepam:

7-chloro-1, 3-dihydro-1-methyl-5-phenyl-2H-1, 4-benzodiazepin-2-one

Chemical Group NameChemical Group Name

• Drugs are sometimes classified by a portion of their chemical structure:– Cephalosporins, phenothiazines,

benzodiazepines • Chemical group names can become

invaluable to a nursing student.

Generic NameGeneric Name

• Assigned by the U.S. Adopted Name Council

• Less complicated and easier to remember

A Drug Has One Generic NameA Drug Has One Generic Name

• Used by many organizations – Food and Drug Administration (FDA)– United States Pharmacopoeia– World Health Organization

• Written in lower case• Example: diazepam

A Drug Has Several Trade NamesA Drug Has Several Trade Names

• Assigned by company marketing the drug

• Short, easy to remember• Also called proprietary, product, or

brand name

A Drug Has Several Trade NamesA Drug Has Several Trade Names

• Drug developer has exclusive rights to name and market a new drug for 17 years in the United States.

• Trade name is capitalized.• Example: a trade name for

diphenhydramine is Benadryl.

Trade NamesTrade Names

• After 17 years, competing companies may sell a generic equivalent drug, sometimes using a different name, which the FDA must approve.

Trade NamesTrade Names

• Trade names can be difficult because many drugs contain similar ingredients.– A combination drug contains more than

one active ingredient.– The rule of thumb is that the active

ingredients in a drug are described by their generic name, which is lowercase.

Table 2.3 Examples of Brand-Name Products Containing Popular Generic Substances

Rights IssuesRights Issues

• A pharmaceutical company with exclusive rights to a drug often prices it very high.

• When rights end, competing companies offer the generic form of the drug for less money.

Rights IssuesRights Issues

• Depending on the state, a pharmacist may offer the generic form of a prescribed drug, or may only be allowed to dispense the exact form written in the prescription.– Drug companies lobby against easy

substitution of generic drugs; consumer advocates lobby the opposite.

Generic vs. Brand-Name DrugsGeneric vs. Brand-Name Drugs

• It is difficult to tell if there is a difference in effect between two forms of a drug, even if dosage is the same.– Inert ingredients may be different.

Generic vs. Brand-Name DrugsGeneric vs. Brand-Name Drugs

• Key to comparison is bioavailability—the physiologic ability of the drug to reach its target cells and produce its effect.

• Measuring how long a drug takes to exert its effect gives a crude measure of bioavailability.

Some States Have a Negative Some States Have a Negative Formulary ListFormulary List

• List of trade-name drugs that pharmacists may not dispense as generic-drug substitutes

• Claim that there are differences in bioavailability between generic and trade-name drugs

• Pharmaceutical companies and some health care practitioners support list.

• Claim that differences could adversely affect patient outcomes

• Laws relating to these lists often change.

• Consumer advocate groups often argue against the Negative Formulary List because of cost savings of generic drugs.

Addiction and DependenceAddiction and Dependence

• Addiction– The overwhelming feeling that drives a

person to use a drug repeatedly• Dependence

– A physiologic or psychologic need for a substance

• Physical dependence– An altered physical condition caused by

the adaptation of the nervous system to repeated drug use

• When the drug is no longer available, the individual expresses physical signs of discomfort known as withdrawal.

• Psychologically dependent– Little physical discomfort when drug is

withdrawn, but intense compelling desire to continue use

Controlled SubstancesControlled Substances

• Controlled substances are drugs that:– Are restricted by the Controlled

Substances Act of 1970– Are frequently abused– Have a high potential for addiction or

dependence– Have restricted use– Are placed into one of five schedules

Controlled Substance Controlled Substance Act of 1970Act of 1970

• Also known as Comprehensive Drug Abuse Prevention and Control Act

• Restricts use of drugs with potential for abuse

• Restricted drugs placed into the five schedules

• Hospitals and pharmacies must maintain complete records of scheduled drugs.

Drug Enforcement Administration (DEA) Drug Enforcement Administration (DEA) Regulates Controlled Substance ActRegulates Controlled Substance Act

• Hospitals and pharmacies must register with DEA.– Must use assigned registration number

to purchase scheduled drugs

Controlled SubstancesControlled Substances

• Anyone convicted of unlawful manufacturing, distributing, and dispensing of controlled substances faces severe penalties.

Scheduled DrugsScheduled Drugs

• Drugs that have a significant potential for abuse are placed into five categories called schedules.– Schedule I drugs have the highest abuse

potential, Schedule V the lowest.

Table 2.4 Examples of Brand-Name Products Containing Popular Generic Substances

Schedule I DrugsSchedule I Drugs

• Restricted to situations of medical necessity, if allowed at all

• Little or no therapeutic value; mostly used for research

Examples of Schedule I DrugsExamples of Schedule I Drugs

• Heroin• LSD• Methaqualone

Schedule II-V DrugsSchedule II-V Drugs

• May be dispersed only in cases where therapeutic value has been determined

• Some Schedule V drugs may be dispersed without a prescription.

Not All Drugs with Abuse Potential Not All Drugs with Abuse Potential Are RegulatedAre Regulated

• Tobacco, alcohol, and caffeine

Schedule II DrugsSchedule II Drugs

• High abuse potential• High potential for physical and

psychological dependence• Therapeutic use with prescription• Some drugs no longer used

Schedule II Drugs Have More Schedule II Drugs Have More Restrictions Restrictions

• Need special order form to obtain• Orders must be written.• Orders must be signed by health care

provider.• Telephone orders to pharmacies are not

permitted.• No refills are permitted; patient must

see health care provider first.

Examples of Schedule II DrugsExamples of Schedule II Drugs

• Morphine• PCP• Cocaine• Methadone• Methamphetamine

Schedule III DrugsSchedule III Drugs

• Moderate abuse potential• Moderate physical dependence• High potential for psychological

dependence• Therapeutic use with prescription

Examples of Schedule III DrugsExamples of Schedule III Drugs

• Anabolic steroids• Codeine with aspirin or Tylenol• Hydrocodone with aspirin or Tylenol• Some barbiturates

Schedule IV DrugsSchedule IV Drugs

• Lower abuse potential• Lower potential for physical and

psychological dependence• Therapeutic use with prescription

Examples of Schedule IV DrugsExamples of Schedule IV Drugs

• Dextropropoxyphene• Pentazocine• Meprobamate• Diazepam• Alprazolam

Schedule V DrugsSchedule V Drugs

• Lowest abuse potential• Lowest physical and psychological

dependence• Therapeutic use without prescription• Examples:

– OTC cough medicines with codeine

Teratogenic Drug ClassificationTeratogenic Drug Classification

• Five categories of risk that a drug poses to a fetus in the case of a pregnant woman taking the drug

• A, B, C, D, and X

Category A DrugsCategory A Drugs

• Controlled studies in women fail to show a risk to the fetus, and the possibility of fetal harm appears unlikely.

Category B DrugsCategory B Drugs

• Animal reproduction studies have not shown a fetal risk or adverse effect. Risks have not been confirmed in controlled studies in women.

Category C DrugsCategory C Drugs

• Either studies in animals have revealed adverse effects on the fetus and there are no controlled studies in women or studies in women and animals are not available.

Category D DrugsCategory D Drugs

• There is confirmation of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk—for example, in a life threatening situation.

Category X DrugsCategory X Drugs

• Animal and human studies have shown fetal abnormalities.

• The drug is contraindicated in women who are or may become pregnant.

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