CORNEAL TISSUE-LEVELS OF TOPICALLY APPLIED CIPROFLOXACIN

The effectiveness of the fluoroquinolone ciprofloxacin is dependent on stromal drug concentrations which exceed the minimum inhibitory conce ntration(90) (MIC(90)). The purpose of this study is to compare cornea l tissue ciprofloxacin levels in patients exposed to three ciprofloxac in dosing regimens before undergoing penetrating keratoplasty. Thirty- one patients were assigned to one of three treatment groups. Group 1 f ollowed a ciprofloxacin dosing regimen compatible with home use [two d rops of 0.3% ciprofloxacin (Ciloxan; Alcon Laboratories, Fort Worth, T X, U.S.A.) every 4 h over a 24-h period]. Groups 2 and 3 followed a mo re tightly controlled dosing regimen designed for a health-care settin g (two drops of Ciloxan applied by a trained professional every 15 min over a 4-h period). In groups 1 and 2, corneal epithelium was left in tact, whereas in group 3 corneas were abraded. Corneal tissue samples were surgically obtained. Excised buttons were frozen and Ciloxan conc entration determined by high-pressure liquid chromatography. Ciloxan c orneal tissue concentrations (mean +/- SD) were 8.82 +/- 8.24 mu g/g t issue in group 1, 166.20 +/- 336.94 mu g/g tissue in group 2, and 938. 30 +/- 1,081.51 mu g/g tissue in group 3. Ciloxan penetration can be i mproved by administering the drug in a controlled setting at 15-min in tervals over a 4-h period. Individual Ciloxan concentrations exceeded the MIC(90) for most key ocular pathogens despite wide variability in all experimental groups.