Aqueous Level of Ofloxacin following Oral Administration using Capillary Zone Electrophoresis

Abstract

Abstract: : Purpose: Endophthalmitis is a most devastating complication from intra-ocular surgery both for the patient and the surgeon. Various ways are employed to minimize the risk of this complication including using povidone-iodine in the conjunctival sac pre-operatively and giving a sub-conjunctival injection of antibiotic immediately at the end of surgery. Oral ofloxacin pre-operatively has been reported to be effective in reducing the risk of endophthalmitis. In this prospective study, using the method of capillary zone electrophoresis, we determined the aqueous level of ofloxacin following oral administration prior to surgery. Methods: Thirty five consecutive patients undergoing cataract surgery under 1 consultant ophthalmologist were enrolled into the study. The Local Ethics Committee’s approval was obtained and all patients had informed consents. One tablet of ofloxacin (400 mg) was given for the patient to take on the day of surgery. The cataract operation proceeded with an instillation of povidone-iodine into the conjunctival sac and the patient was cleaned and draped. Aqueous humour samples were collected via a paracentesis and the anterior chamber was reformed using a viscoelastic. Thereafter the operation proceeded in the usual way. The time from oral administration of ofloxacin to aqueous humour sample collection was recorded. At the end of surgery no sub-conjunctival antibiotic was given although chloramphenicol ointment was given into the conjunctival sac. The aqueous humour samples were then transferred to Eppendorf tubes and kept in the fridge until collected for analysis using the assay method of capillary zone electrophoresis. Results: The mean aqueous concentration of ofloxacin was 0.776 mg/l (range 0.18 – 1.73). This concentration is higher than the MIC ⁹⁰ (the minimum inhibitory concentration required to inhibit growth of 90% of the bacterial isolates tested) for the majority of bacteria responsible for endophthalmitis. The high aqueous concentration of ofloxacin is detectable by 30 minutes following oral administration and remains high for over 4 hours. There were no cases of endophthalmitis in the study group. Conclusions: We have shown that ofloxacin (400 mg) given orally before cataract surgery achieves aqueous levels that exceed the MIC ⁹⁰ for the majority of organisms causing endophthalmitis. In particular, all cases had higher aqueous concentration of ofloxacin than the MIC ⁹⁰ for S. epidermidis.

Keywords: endophthalmitis • antibiotics/antifungals/antiparasitics • bacterial disease