Which term describes the body's processing of a drug through absorption, distribution, metabolism, and excretion?

• A. Pharmacokinetics
• B. Pharmacodynamics
• C. Bioavailability
• D. Toxicology

Answer: (A)

At the heart of this question is how the body handles a drug from administration to elimination. That process is pharmacokinetics, which encompasses absorption, distribution, metabolism, and excretion. Absorption determines how much and how quickly the drug enters the bloodstream; distribution describes how it travels to tissues and organs; metabolism means the body chemically alters the drug, often in the liver, affecting its activity and clearance; excretion is how the drug and its metabolites are finally eliminated, mainly through the kidneys. Understanding pharmacokinetics helps explain the onset, intensity, and duration of a drug’s effect and informs dosing plans.

Pharmacodynamics, by contrast, deals with what the drug does to the body—its effects and mechanisms of action. Bioavailability refers specifically to the portion of the administered dose that reaches systemic circulation. Toxicology is the study of adverse effects and toxic risks of substances.