Abstract
Abstract: :
Purpose: To evaluate possible toxicity of intravitreal Kenalog (commercial Triamcinolone Acetonide) on the retina of albino rabbits during a long-term follow-up. Methods: Twenty-three Albino rabbits treated by intravitreal injection of 0.1 ml Kenalog to one eye and 0.1ml saline to the other eye were studied. According to the source of drug, rabbits were divided first into 2 groups. Rabbits in group A (n=10), and group B (n=5) were treated with Kenalog purchased from two different sources. Eight more rabbits were treated with Kenalog purchased from the same source as for group B, but the drug was stored for 2 weeks prior to injection either at room (~250C) temperature (groups C, n=2) or at 370C (groupD, n=6). Rabbits were examined ophthalmoscopically and by ERG recordings before, 4 hours, 1, 2, 4, 8 and 12 weeks after injection. Some of the animals were followed for longer periods of time (up to 17 weeks). At the end of follow-up, the rabbits were sacrificed and the retinas were prepared for histological examination at the light-microscopic level. Results: Intravitreal Kenalog caused 30% to 60% reduction in the amplitude of the ERG b-wave in all treated eyes. This effect was evident 4 hours to 2 weeks after injection in group A, 4 to 15 weeks after injection in animals of group B, 2 weeks after injection in group C and as soon as 4 hours after intravitreal injection in group D. In all cases, the b-wave amplitude reduction was permanent during the entire follow-up period. No retinal toxicity was noticed in the control eyes. The histological observations supported the ERG findings. Conclusions: Kenalog is retinotoxic to albino rabbits. The time interval until the manifestation of retinal toxicity depends upon storage conditions. However, even when properly stored at the recommended temperature, Kenalog becomes retinotoxic after being exposed to the body temperature inside the rabbit vitreous.
Keywords: drug toxicity/drug effects • retina • electroretinography: non-clinical