Purpose: To evaluate the pharmacokinetic properties of besifloxacin, gatifloxacin, and moxifloxacin in the conjunctival tissue of healthy volunteers after topical application.
Methods: One-hundred eight (108) subjects were randomly assigned to receive one drop of besifloxacin (0.6% suspension), gatifloxacin (0.3% solution), or moxifloxacin (0.5% solution) ophthalmic formulations in one eye prior to conjunctival biopsy. Conjunctival samples were taken from subjects at either 15 minutes, 30 minutes, 2 hours, 6 hours, 12 hours, or 24 hours after dosing.
Results: All three fluoroquinolones reached a peak mean concentration 15 minutes after dosing. The mean concentrations of besifloxacin, gatifloxacin, and moxifloxacin at 15 minutes were 2.30 +/- 1.42 mug/g, 4.03 +/- 3.84 mug/g, and 10.7 +/- 5.89 mug/g, respectively. Concentrations decreased with each subsequent time point. At 24 hours after dosing, concentrations of besifloxacin were measurable in 4 of 6 subjects, compared with 3 of 6 subjects for gatifloxacin and 2 of 6 subjects for moxifloxacin. Besifloxacin had the greatest mean residence time (4.7 hours) in the conjunctival tissue. With regard to methicillin-resistant strains of Staphylococcus aureus and Staphylococcus epidermidis, besifloxacin had the greatest area-under-the-curve (AUC) to MIC(90) ratio. Nine percent (9%) of study subjects (N = 7) experienced a transient reduction in visual acuity.
Conclusion: All three fluoroquinolones were well tolerated and reached levels in the conjunctiva above the MIC(90)s of methicillin-sensitive S. aureus and S. epidermidis for at least 2 hours.
Keywords: besifloxacin; conjunctivitis; fluoroquinolone; minimum inhibitory concentration; pharmacokinetics.