Effect of omeprazole on the pharmacokinetics of oral gemifloxacin in healthy volunteers

This randomized, double-blind, 2-way crossover study investigated the effect of omeprazole on the pharmacokinetics of gemifloxacin, a novel fluoroquinolone. Thirteen healthy male volunteers received a 320 mg oral dose of gemifloxacin after 4 days of dosing with either omeprazole (40 mg once daily) or matching placebo. Blood was sampled for 48 h after dosing for determination of pharmacokinetic parameters. The mean area under the plasma concentration-time curve extrapolated to infinity (AUC(0-infinity)) and maximum plasma concentration (C-max) for gemifloxacin were increased by, on average, 10% (90% confidence interval [Cf], 0.89, 1.36) and 11% (90% CI, 0.87, 1.43), respectively, when gemifloxacin was given after omeprazole compared with after placebo. Neither the time to C-max (T-max) nor the half-life of gemifloxacin appeared to be affected by administration of omeprazole. There were no clinically relevant changes in adverse events, vital signs or the results of laboratory investigations after co-administration of omeprazole compared with placebo. In view of the modest increase in systemic exposure and the likely maximal increases indicated by the Cls, the effect of omeprazole on gemifloxacin pharmacokinetics is not considered to be clinically significant. Gemifloxacin and omeprazole can therefore be co-administered with no requirement for a dose adjustment. Copyright (C) 1999 S. Karger AG, Basel.