Comparison of 2 moxifloxacin regimens for preoperative prophylaxis: Prospective randomized triple-masked trial: Part 1: Aqueous concentration of maxifloxacin

PURPOSE: To evaluate the aqueous concentration of moxifloxacin following 2 dosing regimens of topically administered moxifloxacin hydrochloride ophthalmic solution 0.5% (Vigamox). SETTING: Iladevi Cataract & IOL Research Centre, Ahmedabad, India. METHODS: In this prospective randomized triple-masked clinical trial, 156 patients having cataract surgery were randomly assigned to 1 of 2 regimens of preoperative prophylaxis. In Group A (n = 76), Vigamox was instilled 4 times a day 1 day before surgery plus 1 drop 2 hours before surgery (total of 5 drops). In Group B (n = 76), Vigamox was first instilled 2 hours before surgery and then every 15 minutes for 1 hour (total of 5 drops). In both groups, aqueous samples (0.1 mL) were collected within 2 hours of the first instillation on the day of surgery and stored at -80 degrees C. The antibiotic concentration in all aqueous aspirates was determined using high-performance liquid chromatography. Data were analyzed using the Kolmogorov-Smirnov t test; 95% confidence intervals (CIs) were calculated. RESULTS: The mean aqueous humor concentration of moxifloxacin was 1.58 mu g/mL +/- 0.80 (SD) in Group A and 2.05 +/- 0.72 mu g/mL in Group B (P<.0001; 95% CI, -0.72 to -0.22). CONCLUSIONS: Both dosing regimens produced substantially higher aqueous concentrations than the known minimum inhibitory concentration for Staphylococcus epidermidis. Topical moxifloxacin administered 2 hours before surgery achieved significantly higher aqueous concentrations than topical moxifloxacin administered 1 day before surgery with 1 drop given on the day of surgery.