A Comparison of Fluoroquinolone Penetration into Human Conjunctival Tissue

Introduction: Ocular penetration of newer fluoroquinolones (FQs) has not been fully investigated in humans, especially in regard to conjunctival tissue penetration. The aim of our study was to evaluate the conjunctival permeability of 3 FQs, which do not contain benzalkonium chloride, using excised pterygium tissue. Methods: Patients undergoing pterygium surgery received a single application of one of the following: 0.5%, moxifloxacin (MFLX), 0.3% gatifloxacin (GFLX), or 0.5% levofloxacin (LVFX). Samples of conjunctival tissue were collected 10, 30, or 45 min following administration of the study drug. Each sample was analyzed by high-performance liquid chromatography, and drug concentrations were measured over time. Results: Conjunctival concentration of all 3 FQs was highest 10 minutes after instillation, then gradually decreased. At all time points, MFLX showed the highest conjunctival concentrations among the 3 drugs. Mean MFLX concentrations were 116.7 +/- 28.9, 19.0 +/- 6.3, and 15.9 +/- 4.7 mu g/g at 10, 30, and 45 min, respectively, and were statistically greater than GFLX or LVFX concentrations at 10 and 45 min. Conclusions: All tested FQs achieved peak concentrations within 10 min following administration. Initial peak concentrations of MFLX were greater than either GFLX or LVFX, and concentrations of MFLX remained highest among the 3 FQs throughout the 45-min time window.