Human aqueous and vitreous humour levels of ciprofloxacin following oral and topical administration

Purpose To assess aqueous and vitreous humour ciprofloxacin concentrations following oral and topical administration of ciprofloxacin in patients with non-inflamed cornea and an intact crystalline lens, and to compare the con centrations of the drug given by either route. Methods In this prospective study, 34 patients undergoing pars plana vitrec tomy for various ocular pathologies were divided into two groups. Eighteen patients received 2 drops of 0.3% ophthalmic solution of ciprofloxacin ever y 30 min for 3 h and then every 60 min for the next 3 h, and 16 patients re ceived a single oral dose of 1000 mg ciprofloxacin 6 h before surgery. The aqueous and vitreous humour samples were simultaneously harvested after ora l or topical administration during pars plana vitrectomy to assess penetrat ion of the drug. These samples were assayed for ciprofloxacin concentration s by a method described previously by us using highperformance liquid chrom atography. Results The aqueous and vitreous humour levels of ciprofloxacin were 0.59 /- 0.06 mu g/ml (mean +/- SEM) and 0.64 +/- 0.06 mu g/ml after oral and 0.4 4 +/- 0.07 mu g/ml and 0.22 +/- 0.04 mu g/ml after topical ciprofloxacin ad ministration, respectively. Aqueous humour levels were not statistically si gnificantly different following oral and topical administration (p = 0.069) . However, the vitreous level of the drug after oral administration was sig nificantly higher than that after topical administration (p<0.001). Conclusion Ocular bioavailability of ciprofloxacin in aqueous humour follow ing oral and topical administration is found to be similar when the drug wa s applied as described above. Penetration of ciprofloxacin into vitreous hu mour is less than that into aqueous humour after topical administration.