What is the difference between pharmacokinetics and pharmacodynamics?

The distinction between pharmacokinetics and pharmacodynamics is fundamental in understanding how drugs work in the body. Pharmacokinetics is the study of how the body processes drugs, which includes the processes of absorption, distribution, metabolism, and elimination. This area of study focuses on what the body does to the drug, such as how quickly and efficiently a drug is absorbed into circulation, how it is distributed to tissues, how it is metabolized by the liver, and how it is excreted.

On the other hand, pharmacodynamics involves the study of the effects of drugs on the body, specifically how they achieve their therapeutic effects and the mechanisms by which they produce these effects. This includes the relationship between drug concentration at the site of action and the resulting effect, as well as the potential side effects or adverse reactions.

Therefore, the correct answer accurately reflects that pharmacokinetics studies how the body processes drugs, while pharmacodynamics studies the effects of those drugs on the body. Understanding these definitions provides a clear framework for analyzing drug therapy in clinical practice.