Vitreous penetration of orally administered gatifloxacin in humans

Purpose: To investigate the penetration of gatifloxacin, a novel extended-spectrum fluoroquinolone antibiotic, into the vitreous humor after oral administration. Methods: A prospective, nonrandomized clinical study of 20 consecutive patients scheduled for pars plana vitrectomy surgery between September 2001 and February 2002 at the Cullen Eye Institute, Houston, Texas. Aqueous, vitreous, and serum samples were obtained and analyzed from 20 patients after oral administration of two 400-mg gatifloxacin tablets taken 12 hours apart before surgery. Assays were performed using high-performance liquid chromatography. Results: Mean gatifloxacin concentrations in serum (n=19), vitreous (n=19), and aqueous (n=10) were 4.98 ± 1.14 μg/mL, 1.35 ± 0.36 μg/mL, and 1.09 ± 0.57 μg/mL, respectively. Mean sampling times after oral administration of the second gatifloxacin tablet for serum, vitreous, and aqueous were 2.99 ± 0.73 hours, 3.79 ± 0.81 hours, and 3.71 ± 0.87 hours, respectively. The percentages of serum gatifloxacin concentration achieved in the vitreous and aqueous were 27.13% and 21.85%, respectively. Mean inhibitory vitreous and aqueous MIC₉₀ levels were achieved against a wide spectrum of pathogens, including Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Propionibacterium acnes, Haemophilus influenzae, Escherichia coli, Bacillus cereus, Neisseria gonorrhoeae, Proteus mirabilis, and other organisms. Conclusions: Gatifloxacin is a novel fourth-generation fluoroquinolone antibiotic that has MIC₉₀ levels significantly lower than those of other fluoroquinolone agents. Furthermore, it penetrates well into the vitreous cavity in the noninflamed eye. Potential uses for oral gatifloxacin may include prophylaxis against endophthalmitis in open-globe injuries, surgical prophylaxis against postoperative endophthalmitis, and adjunctive therapy for the current management of bacterial endophthalmitis.