Requirements for pharmacokinetic evaluation of antibiotics in phase I studies

Initial pharmacokinetic studies usually include healthy volunteers to minimize variation generated by diseases. Ethical aspects of initial studies are paramount. The guidelines of the Helsinki Declaration should be followed or even extended. Thorough toxicologic screening in animals is a prerequisite. The use of radioisotopes for pharmacokinetic studies should be limited. The basic design of studies includes cross-over administration of intravenous and oral doses of several sizes. Bioavailability, total area under the serum concentration curve, serum half-life, amount eliminated in urine as active drug, and metabolism are the most important data. The fate of the parent compound and of its possible metabolites in both healthy persons and ill individuals (including those with renal or hepatic dysfunction) should be monitored. Diet may have consequences with regard to recommended dosage schedules. When possible, tissue penetration of antibiotics should be assessed, preferably through the analysis of peripheral human lymph and of suction-blister and peritoneal fluids. Theoretical dosage schedules based on pharmacokinetic assessments in healthy persons should be tested in patients with infectious disease, particularly in those with reduced renal and/or hepatic function.