Experimental intravitreal application of ciprofloxacin in rabbits

Background: Ciprofloxacin (CFLX) is a fluoroquinolone antibiotic with a bro ad antimicrobial spectrum. This study was performed to examine the retinal toxicity of free and liposome-incorporated CFLX in rabbit eyes after intrav itreal injection. Materials and Methods: Free CFLX in doses of 100, 250, 50 0, 1,000 and 2,000 mu g was injected into the midvitreous of rabbit eyes (n = 28). To prolong the intravitreal antibacterial level, CFLX was incorpora ted into multilamellar liposomes: 0.1 ml of this suspension ((=) over cap 2 73.6 mu g CFLX) was injected into the midvitreous of a second group of rabb it eyes (n = 6). The other eye served as a control and received normal sali ne solution or empty liposomes, respectively. Before injection and at the e nd of follow-up an electroretinogram (ERG) was obtained. After a follow-up of 1, 14 and 28 days the animals were perfused with glutaraldehyde and the eyes were examined by light and transmission electron microscopy. Results: Significant reduction of the ERG was observed after 2,000 mu g free CFLX in 4 out of 6 eyes after 14 days. Fourteen days after injection of 2,000 mu g CFLX the central retina showed pigmentary changes in 4 out of 6 eyes. In t he second group the ERG as well as the histologic studies did not reveal an y pathologic changes after injection of liposome-incorporated CFLX compared to the control eyes. Conclusion: In therapeutic doses of 100-500 mu g, fre e CFLX does not have retinal toxicity in rabbit eyes. No retinal toxicity w as observed after intravitreal injection of liposome-incorporated CFLX.