Vitreous and aqueous penetration of orally administered moxifloxacin in humans

Objective: To investigate intraocular penetration of moxifloxacin hydrochloride after oral administration. Methods: Prospective study of 15 patients scheduled for vitrectomy between September and November 2004 at the Barnes Retina Institute, St Louis, Mo. Aqueous, vitreous, and serum samples were analyzed from 15 patients after oral administration of 2 tablets containing 400 mg of moxifloxacin. Assays were performed using high-performance liquid chromatography. Results: The mean +/- SD moxifloxacin concentrations in plasma (n = 15), vitreous (n = 13), and aqueous (n = 13) samples were 3.56 +/- 1.31 mu g/mL, 1.34 +/- 0.66 mu g/mL, and 1.58 +/- 0.80 mu g/mL, respectively. Mean +/- SD sampling times after oral administration of the second moxifloxacin tablet for plasma, vitreous, and aqueous were 2.94 +/- 0.81 hours, 3.77 +/- 0.92 hours, and 3.71 +/- 0.89 hours, respectively. The percentages of plasma moxifloxacin concentration in the vitreous and aqueous were 37.6% and 44.3%, respectively. Minimal inhibitory concentrations against 90% levels were exceeded against a wide spectrum of gram-positive and gram-negative pathogens in the vitreous and aqueous. Conclusions: Moxifloxacin has a spectrum of coverage that encompasses the most common organisms in endophthalmitis. The pharmacokinetic findings of this investigation reveal that orally administered moxifloxacin achieves therapeutic levels in the noninflamed eye. Because of their broad spectrum of coverage, low minimal inhibitory concentration against 90% levels, good tolerability, and excellent oral bioavailability, fourth-generation fluoroquinolones may represent a major advance for managing posterior segment infections.