Penetration of topical and oral ofloxacin into the aqueous and vitreous humor of inflamed rabbit eyes

Purpose: This study aimed to investigate the penetration of topical and ora l ofloxacin into aqueous humor and vitreous humor in post-traumatic endopht halmitis model in rabbits. Methods: A standardized intraocular infection af ter penetrating injury was made in the right eyes of 16 rabbits. Intraocula r infection was induced by intravitreal injection of a suspension of Staphy lococcus aureus. The intact left eyes were maintained as controls. The anim als were divided randomly into two groups. (1) In the topical group, two dr ops of offloxacin 0.3% eyedrops were instilled to both eyes every 30 min fo r 4 h. (2) In the topical-oral group, two doses of 25 mg/kg of ofloxacin at 12-h intervals were given orally, then the protocol of the first group was applied. Aqueous and vitreous humor samples were taken 30 min after the la st drop. Ofloxacin concentrations were measured by using HPLC. Results: Mea n aqueous levels of ofloxacin in control eyes were: 3.25 +/- 2.55 mu g/ml i n topical group, 4.58 +/- 5.39 mu g/ml in topical-oral group. Mean aqueous levels in inflamed eyes were: 5.21 +/- 4.55 mu g/ml in topical group, 10.34 +/- 8.88 mu g/ml in topical-oral group. Mean vitreous levels of ofloxacin in control eyes were: 0.17 +/- 0.07 mu g/ml in topical group, 1.30 +/- 1.23 mu g/ml in topical-oral group. Mean vitreous levels in inflamed eyes were: 0.35 +/- 0.22 mu g/ml in topical group, 3.48 +/- 2.69 mu g/ml in topical-o ral group. There was no significant difference among the groups (P > 0.05), however. Conclusions: The result of this study suggests that oral suppleme ntation of ofloxacin to topical instillation increased the ocular levels of ofloxacin in the post-traumatic endophthalmitis model. Mean drug concentra tions in aqueous and vitreous humors were above the 90% minimum inhibitory concentrations (MIC90) for most of the common microorganisms causing endoph thalmitis in all eyes, except in the vitreous humors of the intact eyes ins tilled topically. (C) 2000 Elsevier Science B.V. All rights reserved.