ABSTRACT
BACKGROUND: The aim of the study was to evaluate the vitreous penetration of two commercially available ophthalmic fluoroquinolones: ofloxacin and levofloxacin. METHODS: This prospective, double-blind, randomized clinical trial comprised 16 patients scheduled for vitrectomy surgery of one eye for macular hole or macular pucker. The patients were randomly assigned to receive topical ofloxacin 0.3% (n=9) or levofloxacin 0.5% (n=7) the day before, one drop at noon, 4 p.m., 8 p.m. and midnight. The next morning, patients were given their assigned masked antibiotic every 5 min for four doses starting 1 h before surgery. The vitreous humour samples, at least 0.3 ml each, were collected 1 h after the administration of the last dose, at the beginning of the pars plana vitrectomy with infusion disconnected. Samples were assayed for ofloxacin and levofloxacin concentrations by a method using high-performance liquid chromatography (HPLC) coupled with single mass spectrometry with electrospray ionization RESULTS: Equal topical administration of levofloxacin yielded 2.5 times higher vitreal concentration than ofloxacin. The mean vitreous concentrations of ofloxacin and levofloxacin were 5.30+/-3.04 (SD) ng/ml and 13.09+/-5.24 ng/ml, respectively (P=0.002). CONCLUSIONS: Equal dosing with topical administration of levofloxacin 0.5% and ofloxacin 0.3% allows better penetration into the vitreous for levofloxacin, but the levels of mean concentrations of each drug did not exceed the MIC(90) or MIC(50) for most ocular pathogenic bacteria in terms of conventional endophthalmitis therapy.
