Penetration of moxifloxacin into the human aqueous humour after oral administration

Aims: To determine the pharmacokinetics of moxifloxacin, a new generation fluoroquinolone, in the anterior chamber of the human uninflamed eye. Methods: 35 patients undergoing cataract surgery received two doses of 400 mg of oral moxifloxacin with a 12 hour interval and were divided into six groups. Moxifloxacin levels in aqueous humour and serum were determined by a microbiological agar well diffusion technique at 2, 4, 6, 8, 10, and 12 hours after the second dose in each group respectively. Results: Mean moxifloxacin levels in the anterior chamber were 1.20 (SD 0.35) mg/ml at the 2 hours group, 1.22 (0.48) mg/ml at the 4 hours group, 1.20 (0.45) mg/ml at the 6 hours group, 1.58 (0.38) mg/ml at the 8 hours group, 1.37 (0.44) mg/ml at the 10 hours group, and 1.23 (0.55) mg/ml at the 12 hours group. The mean ratio of aqueous to serum moxifloxacin level was 38%. Conclusion: Moxifloxacin penetrates well into the anterior chamber of the human uninflamed eye after oral administration, reaching early significant levels, which are maintained for at least 12 hours and are much higher than the MIC90 values of Gram positive and Gram negative pathogens commonly implicated in intraocular infections with the exceptions of fluoroquinolone resistant staphylococci, MRSA, and Pseudomonas aeruginosa.