Abstract
Abstract: :
Purpose: To compare tear film concentrations and ocular tissue penetration after topical administration of gatifloxacin, a 4th generation fluoroquinolone, with ciprofloxacin, a 3rd generation fluoroquinolone in rabbits. Methods: Gatifloxacin 0.3% (GFLX) or ciprofloxacin 0.3% (CIPR) was instilled into rabbit eyes as a single dose or as a multiple dose regimen (QID for 3 days). Samples were obtained at 9 time points (0.5 to 24 hrs after completion of the dosing period (single or multiple); 4 eyes per timepoint) and were assayed for GFLX or CIPR concentrations by a validated LC-MS/MS procedure. Results: In corneal tissues, GFLX achieved a maximum concentration (Cmax) of 4.5 µg/mL (Tmax = 0.5 hr) after single dose, and 7.8 µg/mL (Tmax = 0.5 hr) after multiple doses, or 1.4 and 1.5 times respectively the CIPR values (Cmax = 3.3 µg/mL Tmax = 3 hr and Cmax = 5.1 µg/mL Tmax = 1 hr, respectively). GFLX corneal tissue concentrations integrated over 24 hr (AUC = 28.7 µg·hr/mL) was significantly greater than CIPR (AUC = 20.5 µg·hr/mL) after multiple doses (P<0.011). Cmax of GFLX in aqueous humor was 0.27 µg/mL (Tmax = 1 hr) after a single dose, and 0.54 µg/mL (Tmax = 0.5 hr) after multiple doses, or 0.9 and 2.2 times, respectively the CIPR Cmax values (Cmax = 0.30 µg/mL Tmax = 3 hr and Cmax = 0.25 µg/mL Tmax = 1 hr, respectively). Aqueous humor AUC values for GFLX were significantly greater than CIPR after a single dose (1.05 µg·hr/mL vs. 0.65 µg·hr/mL; P=0.047) and after multiple doses (1.83 µg·hr/mL vs. 0.81 µg·hr/mL; P<0.001). GFLX and CIPR concentrations in tears and conjunctiva were similar. Conclusions: GFLX demonstrated significantly greater penetration than CIPR into corneal tissue and aqueous humor of rabbits. Following topical administration of gatifloxacin 0.3% ophthalmic solution, GFLX concentrations in corneal tissue and aqueous humor achieved or exceeded MICs for many species of ocular pathogens.
Keywords: antibiotics/antifungals/antiparasitics • pharmacology • cornea: basic science