Chapter 1: Introduction to Drugs

The applied branch of this science, pharmacotherapeutics (or clinical pharmacology), specifically addresses the use of drugs—which are chemicals introduced to bring about change—for the treatment, prevention, and diagnosis of human disease. Nursing responsibilities are integral to this field, encompassing drug administration, assessing both therapeutic and adverse effects, intervening to optimize patient tolerability, providing necessary education on drug regimens, and monitoring overall patient care to prevent medication errors. Drug sources are diverse, ranging from natural origins such as plants (e.g., digitalis), animal products (e.g., historically, insulin), and inorganic compounds (e.g., aluminum, iron salts), to synthetic sources often involving genetic engineering to enhance potency and reduce toxicity. The U.S. Food and Drug Administration (FDA) rigorously regulates drug development in the U.S., which begins with preclinical trials on laboratory animals to assess therapeutic activity, toxicity, and teratogenic potential (adverse effects on a fetus). This stage is followed by human studies: Phase I uses healthy volunteers; Phase II tests the chemical on patients with the disease it is designed to treat; and Phase III involves wide-scale use in the clinical setting to identify any unanticipated effects. Following FDA approval, drugs enter Phase IV studies, characterized by continuous evaluation and post-marketing monitoring for unexpected therapeutic or dangerous adverse effects. Drugs are known by three primary names: the chemical name reflecting its structure, the generic name given during the approval process, and the brand name (or trade name) assigned by the developing pharmaceutical company. Legal regulation includes the Controlled Substances Act of 1970, which established five DEA schedules (C-I to C-V) based on the drug’s potential for abuse and dependence. The chapter also distinguishes between generic drugs—which are chemically identical to brand names after the patent expires but may differ slightly in bioavailability—orphan drugs—which treat rare diseases and are developed with financial incentives—and over-the-counter (OTC) drugs, which are available without a prescription but must be used carefully to avoid masking underlying disease, causing drug interactions, or leading to overdose. Finally, safety standards related to pregnancy have evolved, with the FDA phasing out the former pregnancy categories (A, B, C, D, X) in favor of more detailed prescribing information related to risks during fertility, pregnancy, and lactation.