Core Pharmacy Terms and Definitions
Pharmacy terms and definitions describe the language used in drug development, dispensing, and regulation. A prescription is a formal order from a licensed prescriber for a specific medication, dose, and quantity. The United States Pharmacopeia sets official standards for drug identity, strength, and quality. The FDA's Orange Book lists approved drug products and therapeutic equivalents, helping pharmacists and payers compare branded and generic options. FDA drug approval process
Pharmacokinetics defines how the body absorbs, distributes, metabolizes, and excretes a drug, often summarized as ADME. Bioavailability measures the rate and extent a drug reaches systemic circulation compared to an intravenous reference. The World Health Organization maintains the International Nonproprietary Name system to standardize generic drug names globally. In the U.S., pharmacy benefit managers process claims and manage formularies for health plans and employers, influencing which drugs are covered and at what cost.
Common Prescription and Dispensing Definitions
Sig, short for signa, is the label instruction directing the patient how to take the medication, including dose, route, frequency, and duration. A formulary is a list of covered drugs selected by a health plan or institution based on clinical evidence and cost-effectiveness. Tiering classifies drugs into cost levels, with Tier 1 usually preferred generics and Tier 3 specialty drugs carrying higher copays. Specialty pharmacy focuses on high-cost, complex medications for conditions such as cancer, hepatitis C, and rare diseases, often requiring special handling and patient support.
Dispensing accuracy refers to the correct matching of drug, strength, quantity, and label to the prescription order. The Drug Enforcement Administration classifies controlled substances into schedules based on accepted medical use and abuse potential. Schedule II drugs have high abuse risk and strict prescribing rules, while Schedule V drugs have lower potential for dependence. Chain pharmacies such as CVS Health, Walgreens Boots Alliance, and Walmart operate large networks of retail locations and mail-order services across the United States.
Drug Development and Regulatory Definitions
New Drug Application is the formal submission to the FDA for marketing approval, containing preclinical and clinical data on safety and efficacy. Abbreviated New Drug Application allows generic manufacturers to seek approval without repeating costly clinical trials, relying on bioequivalence studies instead. Biologics are complex products derived from living cells, and biosimilars are highly similar versions with no clinically meaningful differences from the reference product. The Hatch-Waxman Act of 1984 streamlined generic drug approval and encouraged market competition by allowing applicants to challenge patents.
Pharmacovigilance is the science of detecting, assessing, and preventing adverse effects of medicines after they reach the market. Post-marketing surveillance uses real-world data from electronic health records, claims databases, and patient registries to identify rare or long-term risks. The FDA Adverse Event Reporting System collects voluntary and mandatory reports from healthcare professionals and consumers. In 2023, the global pharmaceutical market exceeded 1.5 trillion U.S. dollars in annual revenue, with the United States representing the largest share of spending on prescription drugs, according to industry analysis and reports from major consulting firms and research organizations.