The general principles of in-vitro simulation of drug pharmacokinetic profiles for linear one-, two- and multi-compartment models are described. An in-vitro dynamic model constructed on the basis of these, incorporating a novel filtration unit to provide efficient filtration of drugs at constant inoculum size, was used to study the antimicrobial action of sisomicin on Escherichia coli A 20363, in conditions simulating the pharmacokinetic profile observed in humans after a single intramuscular dose of 1 mg/kg.