[Admissable and limited extrapolation of pharmacological and toxicological results on man demonstrated on selected examples (author's transl)].

The results of comparative studies with respect to pharmacological, toxicological, pharmacokinetic and clinico-pharmacological effects of the non-steroid anti-inflammatory drugs 4-[4-(2'-fluorobiphenylyl)]-4-hydroxycrotonic acid and 3-(2'-fluoro-4-biphenylyl)-butyric acid as well as the intrinsic activities of their metabolites in vitro are discussed. The variation in gastrointestinal side effects caused by the two compounds in different species can conveniently be explained in terms of different pharmacokinetic pathways. This leads to a species dependent formation of pharmaco-dynamically active metabolites.