Effect of calcium supplements on the oral bioavailability of moxifloxacin in healthy male volunteers

Objective: To investigate the effect of concomitant calcium administration on the pharmacokinetics and tolerability of moxifloxacin. Design: This was a nonblinded, randomised, single dose, crossover study in healthy male volunteers. Participants: 12 healthy male Caucasians (age 24 to 45 years) were enrolled in the study. Methods: In each of the 2 study periods, each volunteer received a single oral morning dose of moxifloxacin 400mg after an overnight fast. In 1 of the study periods, Ca2+ 500mg (Calcium-Sandoz(R) Forte) was administered immediately before. and 12 and 24 hours after. moxifloxacin (total of 3 doses of Ca2+). The 2 study periods were separated by a washout period of at least 2 weeks. Results: Moxifloxacin was well tolerated throughout the study. There was no difference in the area under the plasma concentration-time curve from zero to infinity [AUC(infinity); geometric mean (SD)] of moxifloxacin [32.2 (1.24) vs 33.0 (1.26) mg.L . h. with vs without Ca2+]. Maximum plasma concentration (C-max) [2.29 (1.27) vs 2.71 (1.33) mg/L, with vs without Ca2+] slightly decreased by approximately 16% and the time to C-max [median (range)] tended to be slightly prolonged [2.5 (0.8 to 3) vs 0.9 (0.5 to 2.5) hours, with vs without Ca2+]. Conclusions: The extent of absorption of moxifloxacin is not affected by concomitant Ca2+ intake, whereas the rate of absorption is slightly reduced, an effect not considered to be of clinical relevance. Hence, moxifloxacin may be administered together with Ca2+ without dosage adjustments or special recommendations.