Species similarities in pharmacokinetics

There are many well documented similarities in the anatomy and physiology of mammalian species. There are also numerous examples in which the equilibrium distribution of foreign chemicals in the body appears to follow principles of thermodynamic partitioning with relatively minor interspecies variations to be expected. Information on metabolic pathways and their kinetic characteristics can be obtained from a variety of in vitro systems. It may be possible to use such information in pharmacokinetic models that incorporate existing knowledge and judgment to predict pharmacokinetics in intact animals including man.