ABSTRACT
The information required to estimate when a drug or chemical is depleted from the animal to safe levels is the realm of the discipline of pharmacokinetics. Pharmacokinetic parameters allow one to determine tissues in which drugs distribute or accumulate. Pharmacokinetics sheds light on the question of interspecies extrapolation. The reference point for pharmacokinetic analysis is the concentration of free, non-protein-bound drug dissolved in the serum as this is the only body fluid from which samples for drug analysis can be readily and repeatedly collected. Saturation of hepatic elimination introduces complexities into pharmacokinetic models. The important consideration in clinical practice is the realization that nonlinear pharmacokinetics may be observed in situations where high doses of drugs or toxicants are involved. Drug elimination is estimated by the pharmacokinetic parameter of total body clearance. Most pharmacokinetic analyses conducted in veterinary medicine utilize the classical linear compartmental approach. Comparative pharmacokinetics is the study of devising strategies for extrapolating parameters of drug disposition across species.
