Effect of Maalox on the bioavailability of oral gemifloxacin in healthy volunteers.
This open, randomized, 4-way crossover study investigated the effect of the antacid Maalox on the bioavailability of gemifloxacin, a novel fluoroquinolone antimicrobial. Sixteen healthy male volunteers received gemifloxacin, 320 mg p.o., alone, 3 h after Maalox administration, or 10 min or 2 h before Maalox administration. Blood was sampled for 48 h after dosing to determine pharmacokinetic parameters. Estimates for the differences between regimens and 95% confidence intervals were calculated using the t-test for paired data. The administration of gemifloxacin 10 min before Maalox resulted in an average 85% reduction in the area under the plasma concentration-time curve from time zero extrapolated to infinity (AUC(0-infinity)), whereas administration 3 h after Maalox produced a decrease in AUC(0-infinity), 15% of which was not considered to be clinically significant. The administration of gemifloxacin 2 h before Maalox had no notable effect on the gemifloxacin AUC(0-infinity) (average increase of 3%). Similar results were seen for the maximum gemifloxacin plasma concentration (C(max)). Neither the time to C(max) nor the half-life of gemifloxacin were notably altered by the administration of Maalox at any time relative to gemifloxacin dosing. There were no clinically important adverse experiences or changes in clinical laboratory parameters during this study. The findings of this study support the dosing recommendation that gemifloxacin can be administered either 2 h or more prior to, or 3 h or more after, the administration of Maalox.