Determination of Ciprofloxacin in Ocular Aqueous Humor by High Performance Liquid Chromatography: Comparison of Topical and Oral Administration

Purpose: Fluoroquinolones are widely used antibiotics for prophylaxis of intra and postoperative infections in individuals undergoing cataract surgery. This study was designed to assess the penetration of ciprofloxacin into the ocular aqueous humor (topical only versus topical and oral administration). Methods: Studied population (n=47) consisted of two groups: group one (n=26) and group two (n=21). Group one received eye drop (one drop every six hours for three days before surgery and on the day of surgery topical medication was administered every 30 minutes with the last drop instillation maximum 4 hours before start of surgery). Group two received a combination of ciprofloxacin comprising of eye drop therapy as describe above plus oral dose (500 mg/twice a day starting three days before operation). Samples of aqueous humor were taken at the start of surgery. Ciprofloxcacin concentration was determined by high performance liquid chromatography (HPLC) with fluorescence detector. Results: Aqueous humor concentrations of ciprofloxacin in the patients who received combinations of eye drops and oral administration doses (mean 0.95 mu g/ml) were significantly higher than patients receiving only eye drops (mean 0.23 mu g/ml, P<0.001). Conclusion: The results for first group were below the minimum inhibitory concentration (MIC) values of Staphylococcus epidermidis, S. aureus, Streptococcus pneumoniae, Pseudomonas aeroginosa, Escherichia coli and Haemophilus influenzae. These results for the second group were over the MIC values of S. epidermidis, S. aureus, Streptococcus pneumoniae and Escherichia coli and below the MIC values of Pseudomonas aeroginosa and Haemophilus influenzae. These results demonstrate that topical ciprofloxacin can penetrate into the aqueous humor but it alone dose not seems to be prophylactically effective against most of the ocular pathogens. In most cases, combining the oral therapy with topical therapy increases the aqueous humor drug level and also is effective significantly against most of the ocular pathogens. This proposal is applicable for drug monitoring in patients undergoing prophylactic antibiotic therapy prior to surgery.