Conjunctival Concentrations of a New Ophthalmic Solution Formulation of Moxifloxacin 0.5% in Cataract Surgery Patients

Abstract

To compare the conjunctival concentrations of moxifloxacin after instillation of a single drop of moxifloxacin ophthalmic solution, 0.5% (Moxi) or a new 0.5% ophthalmic solution formulation (MAF) containing a retention-enhancing agent in patients undergoing cataract surgery. This was a randomized, double-masked, parallel-group study. One hundred thirty patients scheduled for routine phacoemulsification and intraocular lens implantation were randomized to both treatment and post-dose sample collection time points. A single topical drop of Moxi or MAF was instilled in the study eye. At the designated time (0.25, 0.5, 1, 3, or 5 h post-dose), 2 conjunctival biopsy samples were obtained (N = 11-13 per treatment condition). Concentrations of moxifloxacin were determined using a validated ultra-performance liquid chromatography method. Moxifloxacin exposure [maximum mean moxifloxacin concentrations (C(max)) and area under the concentration-time curve (AUC)] was estimated from the observed concentration-time data. The conjunctival moxifloxacin C(max), 43.8 μg/g, for MAF was achieved at 0.25 h. This was 1.8-fold higher than the C(max) for Moxi (24.1 μg/g), which was reached at 0.5 h post-dose. MAF AUC(0-3) was significantly greater than the AUC(0-3) of Moxi [50.5 (μg·h)/g vs. 27.1 (μg·h)/g; P < 0.05]. The conjunctival moxifloxacin C(max) for MAF was 337- to 730-fold greater than the reported minimum inhibitory concentration (MIC(90)) values for Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. The C(max):MIC(90) ratios for Moxi ranged from 185 to 402. Conjunctival AUC(0-24):MIC(90) ratios ranged from 777 to 1,683 for MAF and from 625 to 1,355 for Moxi. The new MAF ophthalmic formulation of moxifloxacin provided higher peak levels of moxifloxacin in the conjunctiva tissue, and larger total tissue exposure than the current, commercially available formulation. The superior penetration of MAF observed in this study could translate into greater eradication of bacteria.