The effects of prolonged acute use and inflammation on the ocular penetration of topical ciprofloxacin

Purpose: To study the aqueous and vitreous penetration of ciprofloxacin aft er prolonged acute topical administration and to investigate the effects of inflammation on drug penetration. Methods: A standardized model of intraoc ular infection after penetrating injury was made in the right eyes of eight rabbits. The intact left eyes were maintained as the control. Two drops of ciprofloxacin 0.3% eyedrops were instilled topically every 1 h for 7 h to all eyes of the rabbits. Aqueous and vitreous samples (100 mu l) were obtai ned half an hour after the last drop. Instillation was continued for 7 h mo re and samples were obtained as before. Drug concentrations were measured u sing HPLC. Results: The mean aqueous humor levels of ciprofloxacin were: in control eyes 1.31 +/- 0.78 mu g/ml after 7 h and 1.85 +/- 1.69 mu g/ml aft er 14 h of instillation; in inflamed eyes 2.18 +/- 1.02 mu g/ml after 7 h a nd 2.91 +/- 2.12 mu g/ml after 14 h. The mean vitreous humor levels were: i n control eyes 0.65 +/- 0.44 mu g/ml after 7 h and 0.72 +/- 0.8 mu g/ml aft er 14 h of instillation; in inflamed eyes 0.67 +/- 0.77 mu g/ml after 7 h a nd 1.01 +/- 0.43 mu g/ml after 14 h. However, the differences among the gro ups were not significant (P > 0.05). Conclusions: Ciprofloxacin penetration into aqueous humor was higher in 14-h topical application than that for 7 h. Inflammation increased the penetration of topical ciprofloxacin into aqu eous while administered for 7 h and into both aqueous and vitreous humor wh ile administered for 14 h. (C) 2000 Elsevier Science B.V. All rights reserv ed.