What is the term for how a drug interacts with the body to cause its effects?

• A. Pharmacodynamics
• B. Pharmacology
• C. Bioequivalence
• D. Pharmacokinetics

Answer: (A)

Pharmacodynamics describes how a drug interacts with the body's targets to produce its effects. It covers the mechanism of action—how the drug binds to receptors or other targets and triggers physiological changes—as well as the relationship between drug concentration and effect (the dose–response). This explains why a drug achieves a certain effect at a given dose, how potent it is, and how effective it can be. Understanding pharmacodynamics helps predict responses, including variations between individuals, based on receptor sensitivity and signaling pathways. Pharmacokinetics, by contrast, is about what the body does to the drug (absorption, distribution, metabolism, excretion), and bioequivalence compares different formulations. So the term for how a drug interacts with the body to cause its effects is pharmacodynamics.