In vivo simulation of human pharmacokinetics in the rabbit

The evaluation of drugs in vivo is often based on experimental models using small animals such as mice, rats and rabbits. However, these models could be improved to correspond more closely to the human situation if the pharmacokinetics of the drugs tested in animals were similar to that observed in humans. The use of a computer-controlled pump allowing an adequate flow of tobramycin and amikacin to be infused into rabbits enabled us to simulate the human pharmacokinetics of these antibiotics in vivo in this study. The function defining the rate of infusion required to perform the simulation of an intravenous bolus was first determined generally and symbolically for linear pharmacokinetic models independently from the number of compartments involved. The practical simulation of a decreasing monoexponential serum profile with a half-life of 2 h (one-compartment model for the human pharmacokinetics of aminoglycosides) was then studied for tobramycin and amikacin on the basis of a two-compartment model in the animal. The kinetics obtained had an apparent elimination half-life of 1.97 and 1.86 h, respectively. Linearity of the semilogarithmic regressions of the profiles obtained was quite sound. Finally, an a posteriori analysis of the pharmacokinetic model and its parameters is proposed on the basis of the results obtained after simulation.