Which term describes the distribution of a drug through the body via the circulatory system after absorption?

• A. Absorption
• B. Distribution
• C. Metabolism
• D. Excretion

Answer: (B)

Distribution describes how a drug moves from the bloodstream to body tissues after it has been absorbed. Once in the circulation, the drug is carried by plasma and diffuses into organs and tissues, with the rate and extent influenced by factors like blood flow to each tissue, the drug’s lipid solubility, its ionization state, and how strongly it binds to plasma proteins. This phase follows absorption and occurs before metabolism and excretion. Absorption is getting the drug into the blood; metabolism is the chemical changes usually in the liver; excretion is removing the drug from the body. So, the distribution through the circulatory system after absorption is described by distribution.