Determination of intraocular safe and nontoxic dosage of propranolol in rabbit's eye by Electroretinography

Propranolol is a non-selective beta adrenergic receptors blocker. In attention to the role of adrenergic receptors on neovascularization in tissues, beta adrenergic receptors blocker such as propranolol was considered to control this process. Previous investigations indicate that propranolol can reduce retinal neovascularization. In this investigation we tried intravitreal administration of propranolol to investigate intraorbital side effects of this drug and determination of the intravitreal safe dose of propranolol for use to retinopathies with neovascularization in future. In this study we use 28 rabbits divided to 4 groups, so each group consisted of 7 rabbits. One Group as control group was given intravitreal injections with normal saline (60 μic.litre). Three other groups as propranolol group’s intake intravitreal injections by propranolol by three different doses (group 1: 15 μic.gram, group 2: 30 μic.gram and group 3: 60 μic.gram). All of injections did in the right eyes of all rabbits. Ophthalmic examinations and ERG were used to assess the effect of intravitreal propranolol injections in all rabbit’s eyes for 4 weeks. The results of retinal examinations indicate that not see any abnormality changes in all groups. But the results of ERG represents significant reduce of b waves in group 3 (P 0.036). This investigation indicates that the dose of 60 μg of intravitreal propranolol is not safe dose and we did not find evidence of retinal toxicity from intravitreal injection of 30μg and less than 30μg propranolol in rabbit’s eyes.