A randomized, investigator-masked clinical trial comparing the efficacy and safety of gatifloxacin 0.3% administered BID versus QID for the treatment of acute bacterial conjunctivitis

Purpose: To compare the efficacy and safety of gatifloxacin ophthalmic solution 0.3% (Zymar) administered BID versus QID in patients with acute bacterial conjunctivitis.Methods: In a randomized, investigator-masked clinical trial, patients diagnosed with bacterial conjunctivitis (based on signs and symptoms) received gatifloxacin either BID or QID for 5 days. Visits were scheduled at day 0, day 3, and day 5. Conjunctival cultures were taken at each visit. The clinical cure rate at day 5 was determined for the entire patient population (primary endpoint). Additionally, clinical cure at day 5 was evaluated for a population of patients defined a priori (per protocol) as being culture positive at baseline and with no substantial protocol deviations. Safety was determined through recording of adverse events. Minimal inhibitory concentrations (MIC) and susceptibility of isolates to gatifloxacin were determined using a broth dilution method. Results: Patient characteristics in both the BID and QID groups (N = 104) were similar in terms of baseline demographics and disposition. The clinical cure rate on day 5 in the entire, intent-to-treat (ITT) population was 86.5% (45/52) in the gatifloxacin BID group and 71.2% (37/52) in the gatifloxacin QID group (95% CI: [–0.03, 30.80]; p = 0.096). In both treatment groups, 5/52 patients (9.6%) reported adverse events. The most common adverse event was conjunctivitis. No serious adverse events were reported. In the a priori-defined per-protocol (PP) population, the clinical cure rate on day 5 was 95.5% (21/22) in the gatifloxacin BID group and 85.7% (18/21) in the gatifloxacin QID group (95% CI: [–7.57, 21.05]; p = 0.294). At baseline, 96.1% (98/102) of the isolates were susceptible to gatifloxacin. The overall MIC90 (mean ± standard error of the mean) was 0.5 ± 1.3 µg/mL.Conclusion: In this study, gatifloxacin 0.3% administered BID was as effective and as safe as gatifloxacin 0.3% administered QID for 5 days for the treatment of bacterial conjunctivitis.