Aqueous humor penetration of fourth-generation fluoroquinolone ophthalmic solutions given by multiple administration in a rabbit model

We investigated the aqueous humor concentration of topically applied gatifloxacin (GFLX) 0.3% and moxifloxacin (MFLX) 0.5% in a rabbit model of surgical and nonsurgical eyes. Topical administration in eyes was performed eight times, at 15-min intervals. Surgical eyes had undergone cataract surgery with the implantation of an intraocular lens (IOL). Aqueous humor was sampled at 5, 30, and 120 min after drug administration. Drug concentrations were determined by high-performance liquid chromatography (HPLC). The GFLX concentrations in surgical eyes at 5, 30, and 120 min post-administration were 12.1, 14.0, and 6.1 g/ml, and those in nonsurgical eyes were 11.3, 11.5, and 7.1 g/ml; there were no differences between surgical and nonsurgical eyes. The concentrations of MFLX in surgical eyes were 46.2, 42.7, and 31.1 g/ml. The concentration of MFLX was higher than that of GFLX at 5 and 120 min post-administration (P < 0.05). A multiple-drop schedule produced much higher aqueous concentrations. There was no difference in drug penetration in eyes that had undergone cataract surgery compared with nonsurgical eyes.