Overview of Pharmacology

By | July 5, 2012

Understanding the basics of pharmacology is an essential nursing responsibility. Pharmacology is the science that deals with the physical and chemical properties, and biochemical and physiologic effects, of drugs. It includes the areas of pharmacokinetics, pharmacodynamics, pharmacotherapeutics, pharmacognosy, and toxicodynamics.

The Drug Online Guide deals primarily with pharmacokinetics, pharmacodynamics, and pharmacotherapeutics — the information you need to administer safe and effective drug therapy (discussed below). Pharmacognosy is the branch of pharmacology that deals with the biological, biochemical, and economic features of naturally occurring drugs. Toxicodynamics is the study of the harmful effects that excessive amounts of a drug produce in the body; in a drug overdose or drug poisoning, large drug doses may saturate or overwhelm normal mechanisms that control absorption, distribution, metabolism, and excretion.

Drug Nomenclature

Most drugs are known by several names — chemical, generic, trade, and official — each of which serves a specific function. (See How drugs are named.) However, multiple drug names can also contribute to medication errors. You may find a familiar drug packaged with an unfamiliar name if your institution changes suppliers or if a familiar drug is newly approved in a different dose or for a new indication.

How drugs are named

A drug’s chemical, generic, trade, and official names are determined at different phases of the drug development process and serve different functions. For example,the various names of the commonly prescribed anticonvulsant divalproex sodium are:

Chemical name: Pentanoic acid, 2-propyl-, sodium salt (2:1) or (C16H3104Na)

Generic name: divalproex sodium

Trade name: Depakote

Official name: Divalproex Sodium Delayed-Release Tablets, USP

A drug’s chemical name describes its atomic and molecular structure.The chemical name of divalproex sodium — pentanoic acid, 2-propyl-, sodium salt (2:1), or C16H3104Na (pronounced valproate semisodium) — indicates that the drug is a combination of two valproic acid compounds with a sodium molecule attached to only one side.

Once a drug successfully completes several clinical trials, it receives a generic name, also known as the nonproprietary name. The generic name is usually derived from but shorter than the chemical name. The United States Adopted Names Council is responsible for selecting generic names, which are intended for unrestricted public use.

Before submitting the drug for FDA approval, the manufacturer creates and registers a trade name (or brand name) when the drug appears ready to be marketed. Trade names are copyrighted and followed by the symbol ® to indicate that they’re registered and that their use is restricted to the drug manufacturer. Once the original patent on a drug has expired, any manufacturer may produce the drug under its own trade name.

A drug’s official name is the name under which it’s listed in the United States Pharmacopoeia (USP) and the National Formulary (NF).

Drug Classification

Drugs can be classified in various ways. Most pharmacology textbooks group drugs by their functional classification, such as psychotherapeutics, which is based on common characteristics. Drugs can also be classified according to their therapeutic use, such as antipanic or antiobsessional drugs. Drugs within a certain therapeutic class may be further divided into subgroups based on their mechanisms of action. For example, the therapeutic class antineoplastics can be further classified as alkylating agents, antibiotic antineoplastics, antimetabolites, antimitotics, biological response modifiers, antineoplastic enzymes, and hormonal antineoplastics.