Potential applications of pharmacokinetics toward minor species-use approvals: human food safety

Pharmacokinetic studies may provide useful information in terms of drug disposition but there has not been enough basic work done to enable CVM to use pharmacokinetics to predict tissue residues and assign withdrawal periods. Much carefully controlled work would need to be conducted to determine the correlations between tissue residues and plasma concentrations for a single drug, for a class of drugs, for differing dose levels, and for extrapolations between species. Conducting good pharmacokinetic studies requires expertise in the area and is not simply a matter of taking blood samples and measuring levels of a drug. In addition, CVM has not established any criteria for determining which studies are adequate to define the relationship between plasma levels of a drug and tissue residues. At this point, for drug approvals in minor species, it is much easier and less time consuming to conduct tissue residue studies in the target animal.