Which term describes the movement of a drug from the bloodstream into body tissues?

• A. Absorption
• B. Distribution
• C. Pharmacokinetics
• D. Pharmacodynamics

Answer: (B)

Distribution describes the movement of a drug from the bloodstream into body tissues. After a drug enters the circulation, it spreads to organs and tissues based on blood flow, the ability of the drug to cross capillary walls, and its affinity for tissues or proteins. This step is a core part of pharmacokinetics (the ADME framework: absorption, distribution, metabolism, excretion) and helps determine how much drug reaches target sites and how long it remains in the body. Drugs that are highly lipid-soluble or that bind to tissue components tend to distribute more widely, affecting the volume of distribution. By contrast, absorption is about entry into the bloodstream from the administration site, and pharmacodynamics concerns the drug’s effects on the body, not its movement between compartments.