THE USE OF IN-VITRO METHODS FOR STUDYING DRUG-METABOLISM TO REPLACE ANIMAL STUDIES AS PART OF VETERINARY MEDICINES PRODUCT LICENSE APPLICATIONS

It is currently necessary to carry out drug metabolism studies in the target species as part of veterinary Product Licence Applications (PLA ). Such studies use large numbers of animals. Studies with pig and rat liver homogenates obtained from animals slaughtered for human consump tion have demonstrated that antipyrine shows the same metabolic differ ences between these species as would be expected in vivo. Continuation of these studies in sheep liver homogenates demonstrated species diff erences in the metabolism of antipyrine between sheep and pigs. In add ition, ruminant isolated cell systems have been used to demonstrate di fferences in sulfadimidine metabolism between rats, goats, sheep and c attle. With the increasing availability of farm-animal isolated hepato cyte systems and mounting evidence that species differences in vitro r eflect the in vivo situation, the time is right for such data to be su bmitted as part of veterinary medicine PLA.