Chapter 2 - Drug Classes and Schedules

Characteristics of an Ideal Drug

Effectiveness - produces a rapid, predictable response at relatively low doses.

Safety - does not produce harmful effects, quickly eliminated from the body, no drug-drug or drug-food interactions.

Other Factors - taken conveniently (orally), taken infrequently (once a day) and for a short length of time, inexpensive.

Drug Application

Indications - the conditions to which a drug is approved.

Health providers want to prescribe drugs that are the most effective, safest, and most convenient.

Therapeutic Classification

Organization based on therapeutic usefulness.

Examples: Anticoagulants - inhibit blood clotting, Antihypertensives - lower blood pressure, Antiarrhythmics - restore normal cardiac rhythm.

Pharmacologic Classification

Organization based on the way drug works at the molecular, tissue, or body system level.

Examples: Diuretic - lowering plasma volume, vasodilator - dilating peripheral blood vessels, ACE-inhibitor - blocking hormonal activity.

Prototype Drug Approach

Prototype drug used as a comparison.

Studying the prototype helps predict the actions, side effects, and clinical applications of other drugs in the group.

Chemical Naming of Drugs

Nomenclature assigned using established guidelines.

Only one chemical name conveys clear, concise information about the drug.

Example: 7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepine-2-one.

In some cases, the chemical name is used (i.e., sodium chloride) or they may be classified by a portion of the chemical structure (i.e., cephalosporins).

Generic Naming of Drugs (Nonproprietary)

Approved by Health Canada.

Less complicated and easier to remember.

Biosimilars are not called generic medications; they use the generic name followed by 4 lower case letters (i.e., infliximab-abda).

Trade Naming of Drugs (Proprietary or Brand)

Usually short and assigned by the company marketing the drug.

Brand Name Drugs vs Generic Equivalents

Drug formulations are not always the same despite dosage being identical.

“Filler” ingredients may be different.

Need to show bioequivalence.

Bioequivalence of Drug Products

Rate and extent of absorption should not show significant differences.

Simple cross over study (only 12-24 healthy subjects).