COMPARATIVE INTRAOCULAR PENETRATION OF TOPICAL AND INJECTED CEFUROXIME

Aims - The choice of a prophylactic antibiotic for cataract surgery is dependent on its antibacterial activity and tissue penetration. The i nfluence of the route and timing of administration of cefuroxime on it s intraocular concentrations was examined. Methods - 120 patients were recruited before cataract surgery into a prospective trial to compare the anterior chamber concentration of cefuroxime at a fixed time afte r adminstration by three routes. In a further 110 patients, the interv al before sampling was varied in order to permit an examination of the kinetics of penetration. In another 10 patients, cefuroxime was given topically at the completion of surgery to assess the effect of a corn eal wound on aqueous penetration. Cefuroxime concentrations were measu red by high performance liquid chromatography on 0.2 ml samples of aqu eous aspirated from the anterior chamber. Mean aqueous concentrations of cefuroxime for each group were compared using Student's t test. Res ults - After 25 mg cefuroxime, mean aqueous concentrations increased i n the order forniceal (< 0.01 mu g/ml) < topical (0.18 mu g/ml) < subc onjunctival (2.31 mu g/ml) when sampled 12-24 minutes after administra tion. Aqueous concentrations of cefuroxime reached a peak between 80 a nd 110 minutes after both forniceal and peribulbar injection but were still rising at this time after subconjunctival injection. Topical app lication of 12.5 mg cefuroxime to eyes with a 10 mm corneal wound resu lted in a mean aqueous concentration of 9.34 mu g/ml.Conclusion - In t he intact eye, only subconjunctival injection resulted in clinically s ignificant aqueous concentrations of cefuroxime (> 1 mu g/ml) between 12 and 24 minutes after administration. For all routes, maximal aqueou s concentrations were delayed by at least 80 minutes from administrati on. In the presence of a corneal wound, high aqueous levels of cefurox ime were rapidly attained after topical application.