Which statement best defines excretion?

Which statement best defines excretion?

• A. The body's distribution to tissues
• B. The body's inactivation of a drug via enzymatic degradation
• C. The process by which a drug is absorbed
• D. The body's elimination of a drug (primarily in the kidneys and liver, and in the feces)

Answer: (D)

Excretion is the body's elimination of a drug from the system. After a drug is absorbed and distributed, it must be removed to end its effects and prevent buildup. The main routes are the kidneys, where the drug or its metabolites are excreted into urine, and the liver, which can secrete substances into bile that’s eliminated in feces. Some drugs may exit via other routes, but excretion centers on removing the drug from the body rather than how it gets distributed, metabolized, or absorbed. This definition—elimination through the kidneys and liver into feces—best captures what excretion means.

Excretion is the body's elimination of a drug from the system. After a drug is absorbed and distributed, it must be removed to end its effects and prevent buildup. The main routes are the kidneys, where the drug or its metabolites are excreted into urine, and the liver, which can secrete substances into bile that’s eliminated in feces. Some drugs may exit via other routes, but excretion centers on removing the drug from the body rather than how it gets distributed, metabolized, or absorbed. This definition—elimination through the kidneys and liver into feces—best captures what excretion means.