Abstract
Purpose: :
To evaluate the retinal toxicity of varying doses of rapamycin when injected intravitreally in rabbits. Rapamycin, a potent immunosuppressive agent with significant antitumor and antiangiogenic properties, is clinically approved for the prevention of organ transplant rejection.
Methods: :
Twelve New Zealand albino rabbits were used for this study and divided into four groups. The animals were treated according to the ARVO guidelines on the care and use of animals in research. Four different doses of rapamycin were prepared in 0.1 ml: 20 µg, 50 µg, 200 µg, and 1,000 µg. Each concentration was injected in one eye of each of three rabbits, and 0.1 ml volume of sterile balanced saline solution was injected into the contralateral eyes in each group. A slit–lamp and funduscopic examination was performed and the animals were observed for two weeks for signs of infection, inflammation, and toxicity. Baseline electroretinography (ERG) was performed before the drug treatment and on day 14, before the animals were euthanized. The eyes were enucleated and prepared for light microscopy.
Results: :
Histological and ERG findings revealed no retinal toxicity in the eyes given 20 µg /0.1 ml of rapamycin. The eyes given higher doses of rapamycin showed evidence of toxicity.
Conclusions: :
Intravitreal rapamycin appears to be nontoxic to the retina of albino rabbits in a concentration of 20 µg.
Keywords: drug toxicity/drug effects • retinal neovascularization • neovascularization