Concentrations of besifloxacin, gatifloxacin, and moxifloxacin in human conjunctiva after topical ocular administration

Gail Torkildsen¹, Joel W Proksch², Aron Shapiro³, Stephanie K Lynch³, Timothy L Comstock²

¹Andover Eye Associates, Andover, Massachusetts, USA; ²Bausch and Lomb, Inc., Rochester, New York, USA; ³Ora, Inc., Andover, Massachusetts, USA

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 μg/g, 4.03 ± 3.84 μg/g, and 10.7 ± 5.89 μg/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 MIC₉₀ 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 MIC₉₀s of methicillin-sensitive S. aureus and S. epidermidis for at least 2 hours.

Keywords: besifloxacin, fluoroquinolone, conjunctivitis, pharmacokinetics, minimum inhibitory concentration