Pharmacodynamics is the study of how the drug

• A. How the drug affects the body
• B. How the body affects the drug
• C. How the drug is metabolized
• D. How the drug is excreted

Answer: (A)

The main concept tested is what the drug does to the body. Pharmacodynamics covers the drug’s effects, how it produces those effects, and the mechanisms behind them—such as receptor binding, activation or inhibition of targets, and the relationship between dose and response. For example, a drug might lower blood pressure by blocking a receptor or changing enzyme activity, and pharmacodynamics explains why those effects occur and how strong they are at different doses.

This is different from pharmacokinetics, which describes what the body does to the drug—how it is absorbed, distributed, metabolized, and excreted. The choices about metabolism and excretion describe pharmacokinetic processes, not pharmacodynamics.