ABSTRACT
It might be considered paradoxical to include techniques in vitro in a discussion on investigations of metabolism and distribution of novel compounds. Studies in vivo usually comprise the greater part of toxicological investigations on novel compounds, and experiments in vitro cannot, of course, simulate the distribution, or pharmacokinetic, aspect of the situation in vivo. Moreover, such studies are not specified as a regulatory requirement in any particular context. In spite of these limitations and peculiarities, the techniques to be described offer a valuable adjunct to the studies in vivo. However, it is absolutely essential to define the precise objectives of the study before suggesting suitable approaches and techniques, since it is these objectives, rather than any specific regulatory guidelines, which will determine the experimental protocols used.
