Penetration of gatifloxacin eye drops into the aqueous humor in humans.

The authors topically administered gatifloxacin (GFLX) into the eye before cataract surgery and measured the concentrations of this agent to determine its penetration into aqueous humor. Seventy-seven patients with age-related cataracts who underwent cataract surgery were enrolled in this study. They received 0.3% GFLX ophthalmic solution 4 times at 30-min intervals, beginning 2 h before surgery. Aqueous humor was aspirated from the anterior chamber and assayed for GFLX concentration using high-performance liquid chromatography. The mean intraoperative GFLX concentration in aqueous humor was 0.485 +/- 0.328 microg/mL. GFLX level was 0.573 +/- 0.367 microg/mL in elderly patients, at least 70 years of age, and was significantly higher than that (0.322 +/- 0.135 microg/mL) in the patients less than 70 years old. This concentration was close to or higher than the minimum inhibitory concentrations required to inhibit the growth of 90% of major pathogens of endophthalmitis (MIC90), such as Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecalis associated with poor prognosis, other than Staphylococcus epidermidis, Pseudomonas aeruginosa, and MRSA (methicillin-resistant S. aureus) in vitro. The GFLX concentrations found in aqueous humor samples were sufficient to kill bacteria other than S. epidermidis, P. aeruginosa, and MRSA in vitro.