The pharmacokinetic basis of optimal antibiotic dosage.

Pharmacokinetic parameters play an important part in the design of an optimal dosage schedule for a drug. These parameters are only of use to the clinician if they can be obtained reliably and without too much experimental or mathematical effort, and their predictive value is independent of elaborate pharmacokinetic models. The three cardinal parameters of clearance (CI), total volume of distribution (Vss) and mean time (T), are defined and different methods are described for their assessment in clinical practice. A more operational method for estimating T than the one recorded in the literature is recommended. The value of this new method is demonstrated by means of an evaluation of data on gentamicin from the literature which have not already been analysed pharmacokinetically, and a comparison with results obtained by classical and more costly methods.