Four multiple dose studies involving 102 healthy volunteers were reviewed to determine the sources of intersubject variability in the pharmacokinetics of temafloxacin. As a result of the preferential distribution of temafloxacin into muscle, liver and kidney compared with adipose tissue, the best anthropometric explanatory variable was found to be lean body mass, rather than total body mass or body surface area. Single dose studies have confirmed that the distribution volume of temafloxacin is smaller in subjects in whom the lean body mass: total body mass ratio is low, notably in females, the elderly, and those with hepatic impairment. Average creatinine clearance for the volunteers included in this analysis was normal (109 ± 29 mlfmin), and renal function was only a marginally significant covariate; however, renal clearance accounts for 60 to 70% of total clearance (CLT) and has been shown to be a major factor in the elderly, as well as in patients with renal or hepatic impairment. Since temafloxacin is partially reabsorbed renally, urine flow rate was found to be a potentially important secondary factor. Overall, the pharmacokinetics of temafloxacin are essentially linear, with steady-state plasma concentrations at trough (C~in) and 2h postdose (Cl~) averaging slightly more than 0.5 and 1.0 mgjL per 100mg administered every (q) 12h. For example, mean C~in and peak steady-state plasma concentration (C~aJ values after administration of temafloxacin 600mg ql2h were 3.3 ± l.l and 6.2 ± 1.8 mgjL, respectively. Total apparent clearance (CLTjF) and the terminal elimination half-life (tv,) averaged II Ljh (184 mlfmin) per 55kg lean body mass and 8.4h, respectively. Considering that the data reviewed came from 4 studies with doses ranging from 100 to 800mg ql2h, the intersubject coefficients of variation were low for an orally administered drug, ranging from 15.4% for tv" 20.6% for cl~, 21.2% for CLT/F and 25% for C~in.