RESUMEN
AIMS: To investigate the penetration of ciprofloxacin via different modes of administration into the aqueous humour using capillary zone electrophoresis and to determine its prophylactic role in ophthalmic surgery. METHODS: A prospective study was conducted of 84 patients, divided into two groups, undergoing routine cataract surgery and intraocular lens implantation. Forty patients received 750 mg ciprofloxacin orally the evening before and on the morning of surgery 12 h apart. Forty-four patients received one drop of 0.3% topical ciprofloxacin 90 and 30 min prior to surgery. At the commencement of surgery 0.1-0.2 mL of aqueous fluid was sampled from the anterior chamber and assayed for ciprofloxacin concentration using capillary-zone electrophoresis. RESULTS: The concentration of ciprofloxacin in the group receiving topical doses was less than 0.1 micro g/mL, which is well below the minimum inhibitory concentration for cipro-floxacin inhibiting 90% (MIC90) of strains of Staphylococcus epidermidis (0.4 micro g/mL). The mean concentration of ciprofloxacin in the aqueous humour of the oral group was 0.26 micro g/mL with a standard deviation of 0.12 micro g/mL (range 0.09-0.67 micro g/mL) with only 12.5% achieving levels higher than MIC90 for S. epidermidis. CONCLUSION: The topical ciprofloxacin 0.3% as given in this study achieved poor aqueous humour concentration. Oral ciprofloxacin given in this regime should not on its own be considered adequate prophylaxis in intraocular surgery. Capillary zone electrophoresis can be used as an alternative tool to the existing high-pressure liquid chromatography methods for analysing ciprofloxacin level in the aqueous humour.