What term refers to the biochemical or physiological event after drug binding?

• A. Drug response
• B. Onset of action
• C. Pharmacokinetics
• D. Placebo effect

Answer: (A)

After a drug binds to its target, the actual biochemical or physiological change it produces is the drug response. This is the pharmacodynamic effect—the body’s reaction to the drug binding, which can be therapeutic or adverse. Onset of action describes how long it takes for these effects to begin, not the effect itself. Pharmacokinetics covers how the body handles the drug (absorption, distribution, metabolism, excretion), which influences the magnitude and duration of the response but isn’t the response. The placebo effect is a psychological or perceptual improvement related to expectations, not a direct result of binding to a target. So the term that refers to the biochemical or physiological event after drug binding is the drug response.