APA Dictionary of Psychology

n. the rate of elimination of a drug from the body in relation to its concentration in a body fluid, as expressed by the equation CL = rate of elimination/C, where C is the concentration of the drug in the body fluid. Clearance is additive, that is, drugs are eliminated by various mechanisms (renal, hepatic, etc.) at differing rates; thus, total clearance is the sum of clearance from each individual organ system.