Comparison of aqueous humour and vitreous humour levels of two 0.3% ciprofloxacin eyedrops

Background: Two ophthalmic solutions of 0.3% ciprofloxacin eyedrops are ava ilable in Turkey: Ciloxan and Siprogut. The objective of this study was to compare the concentrations of drug produced by the two products in the aque ous humour and vitreous humour after local administration. Methods: Twenty-one patients undergoing primary vitreoretinal surgery recei ved either Ciloxan (10 patients) or Siprogut (11 patients). Six hours befor e surgery, two drops of solution were instilled onto the operative eye. Dro ps were then instilled every 30 minutes for the first 3 hours and then hour ly for the next 3 hours. Aqueous and vitreous samples were collected 30 min utes after administration of the last dose and were assayed for ciprofloxac in concentration by means of high-performance liquid chromatography with fl uorometric detection. Results: The mean aqueous humour concentrations of Ciloxan and Siprogut wer e 0.36 (standard error of the mean [SEM] 0.09) mu g/mL and 0.44 (SEM 0.17) mu g/mL respectively. The corresponding vitreous humour concentrations were 0.21 (SEM 0.05) mu g/mL and 0.22 (SEM 0.06) mu g/mL. Neither of these diff erences was statistically significant. The aqueous and vitreous levels of b oth products exceeded the minimum inhibitory concentrations for certain bac terial species that frequently cause intraocular infections. Interpretation: Our results show that the ocular bioavailability of Ciloxan and Siprogut after local administration is equivalent. Penetration of cipr ofloxacin into the vitreous humour seems to be poorer than that into the aq ueous humour.