Background: Ciprofloxacin (CFLX) is a fluoroquinolone antibiotic with a broad antimicrobial spectrum. This study was performed to examine the retinal toxicity of free and liposome-incorporated CFLX in rabbit eyes after intravitreal injection.
Materials and methods: Free CFLX in doses of 100, 250, 500, 1,000 and 2,000 microg was injected into the midvitreous of rabbit eyes (n = 28). To prolong the intravitreal antibacterial level, CFLX was incorporated into multilamellar liposomes: 0.1 ml of this suspension ( wedge 273.6 microg CFLX) was injected into the midvitreous of a second group of rabbit eyes (n = 6). The other eye served as a control and received normal saline solution or empty liposomes, respectively. Before injection and at the end 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 microg free CFLX in 4 out of 6 eyes after 14 days. Fourteen days after injection of 2,000 microg CFLX the central retina showed pigmentary changes in 4 out of 6 eyes. In the second group the ERG as well as the histologic studies did not reveal any pathologic changes after injection of liposome-incorporated CFLX compared to the control eyes.
Conclusion: In therapeutic doses of 100-500 microg, free CFLX does not have retinal toxicity in rabbit eyes. No retinal toxicity was observed after intravitreal injection of liposome-incorporated CFLX.