PENETRATION OF TOPICALLY APPLIED CIPROFLOXACIN, NORFLOXACIN, AND OFLOXACIN INTO THE AQUEOUS-HUMOR

Purpose: To determine the intraocular penetration of topically applied fluoroquinolone antibiotics into aqueous humor. Methods: Thirty-two p atients undergoing cataract extraction received either 0.3% ciprofloxa cin, 0.3% norfloxacin, or 0.3% ofloxacin topical drops. The patients w ere given two drops 90 minutes preoperatively and two drops 30 minutes preoperatively. At the time of surgery, 0.1 ml aqueous fluid was aspi rated from the anterior chamber and immediately stored at -70 degrees C. Results: Concentrations of ciprofloxacin, norfloxacin, and ofloxaci n were determined using a broth dilution bioassay. Morganella morganii with a known minimal inhibitory concentration was used to assay cipro floxacin and norfloxacin levels. Salmonella enteritidis with a known m inimal inhibitory concentration was used to assay ofloxacin levels. To pically applied ciprofloxacin achieved a mean aqueous level of 0.072 m u g/ml (range, 0.02-0.153 mu g/ml). One sample was below the sensitivi ty of the bioassay. Topical norfloxacin achieved a mean aqueous level of 0.0570 mu g/ml (range, 0.046-0.10 mu g/ml). Seven samples did not r each the sensitivity of the bioassay. Topical ofloxacin achieved a mea n level in the aqueous humor of 0.338 mu g/ml (range, 0.078-0.625 mu g /ml). There was no statistically significant difference in intraocular aqueous humor levels of ciprofloxacin versus norfloxacin (P > 0.05). Topical ofloxacin achieved aqueous humor levels significantly higher t han either ciprofloxacin or norfloxacin (P < 0.004). Conclusion: Of th e currently available topical fluoroquinolone antibiotics, ofloxacin a chieves the highest aqueous humor concentrations.