Which statement about PK and PD definitions is true?

Which statement about PK and PD definitions is true?

• A. Pharmacokinetics is how the body affects the drug; Pharmacodynamics is how the drug affects the body
• B. Pharmacokinetics is how the drug affects the body; Pharmacodynamics is how the body affects the drug
• C. Pharmacokinetics is about market price; Pharmacodynamics is about patient satisfaction
• D. Pharmacokinetics is the study of adverse events; Pharmacodynamics is the study of placebo effects

Answer: (A)

In pharmacology, the distinction between how the body handles a drug and what the drug does to the body is fundamental. Pharmacokinetics describes the processes that affect the drug as it moves through and is eliminated by the body—absorption, distribution, metabolism, and excretion. In contrast, pharmacodynamics is about the drug’s effects on the body—the mechanism of action, the relationship between dose and effect, and the resulting therapeutic or adverse responses. So the statement that pharmacokinetics is how the body affects the drug and pharmacodynamics is how the drug affects the body captures the core definitions. The other options mix up these roles or introduce unrelated concepts like market price or placebo effects, which aren’t part of the PK/PD definitions.

In pharmacology, the distinction between how the body handles a drug and what the drug does to the body is fundamental. Pharmacokinetics describes the processes that affect the drug as it moves through and is eliminated by the body—absorption, distribution, metabolism, and excretion. In contrast, pharmacodynamics is about the drug’s effects on the body—the mechanism of action, the relationship between dose and effect, and the resulting therapeutic or adverse responses.

So the statement that pharmacokinetics is how the body affects the drug and pharmacodynamics is how the drug affects the body captures the core definitions. The other options mix up these roles or introduce unrelated concepts like market price or placebo effects, which aren’t part of the PK/PD definitions.