Absorption of topical moxifloxacin ophthalmic solution into human aqueous humor

Purpose: To investigate the absorption of moxifloxacin into human aqueous humor after administration of moxifloxacin hydrochloride ophthalmic solution, 0.5% as base. Methods: Cataract patients were randomly allocated to receive 1 drop every 15 minutes for 4 doses before surgery (group 1) or 1 drop 4 times per day on the day before surgery plus the same preoperative regimen as group 1 (group 2). The last dose was administered 0.25, 0.50, 1, 2, or 3 hours before aqueous humor sampling. Samples from 30 patients per group were analyzed by a validated HPLC/MS/MS method. Results: For group 1, the mean +/- SD C-max was 1.50 +/- 0.75 mu g/mL and occurred at 0.5 hour after dosing. The mean C-max for group 2 was 1.74 +/- 0.66 mu g/mL and was reached at 1 to 2 hours. Mean AUC(0-3h) for groups I and 2 were 3.16 +/- 0.29 and 4.41 +/- 0.48 mu g-h/mL, respectively. The difference in AUC(0-3h) was statistically significant (P = 0.04), but the difference in C-max was not. Conclusions: Topical moxifloxacin was well absorbed. Maximum moxifloxacin concentrations were approximately 30 times higher than the median MICs for common pathogens in bacterial endophthalmitis, indicating that either regimen may provide sufficient concentrations to prevent postoperative endophthalmitis.