VANCOMYCIN LEVELS IN THE VITREOUS CAVITY AFTER INTRAVENOUS ADMINISTRATION

PURPOSE: We studied the effects of inflammation, repeated antibiotic d oses, and the surgical status of the eye on penetration of vancomycin hydrochloride into the rabbit vitreous cavity after intravenous admini stration. METHODS: We studied three anatomic states (phakic, aphakic, and aphakic, vitrectomy-treated eyes) subdividing each into inflamed a nd noninflamed groups. Intravenous vancomycin hydrochloride (15 mg/kg of body weight) was administered every 12 hours for 48 hours. Eyes wer e harvested for the assay of vitreous cavity antibiotic levels at vari ous intervals from one to 49 hours. We determined concentrations and c alculated mean values and S.E.M. RESULTS: Therapeutic levels were not established in the vitreous cavity at any time period in the two phaki c groups. At 25 hours, the inflamed aphakic eyes had concentrations of 5.05 +/- 1.9 mu g/ml and the control noninflamed aphakic eyes 4.5 +/- 1.23 mu g/ml; slight increases were found by 49 hours. Concentrations tested in the aphakic, vitrectomy-treated eyes at two, 13, 25, and 49 hours demonstrated progressive increases both in the inflamed eyes (5 .4 +/- 2.4 mu g/ml, 9.64 +/- 4.25 mu g/ml, 9.2 +/- 3.96 mu g/ml, 10.34 +/- 4.49 mu g/ml) and noninflamed eyes (3.52 +/- 2.1 mu g/ml, 5.4 +/- 1.96 mu g/ml, 6.8 +/- 2.53 mu g/ml, 8.7 +/- 5.44 mu g/ml). CONCLUSION S: Vitreous vancomycin concentrations in aphakic and aphakic, vitrecto my-treated eyes after intravenous administration exceed the minimal in hibitory concentrations for the usual gram positive pathogens that cre ate endophthalmitis, suggesting a role for intravenous vancomycin in t he treatment of bacterial endophthalmitis.