Effect of topically applied nimodipine on the intraocular pressure on ocular normotensive and betamethasone-induced hypertensive eyes in rabbits

Abstract

Glaucoma is a leading cause of irreversible blindness worldwide. Lowering intraocular pressure (IOP) is the only strategy documented to delay the appearance and retard the progression of vision loss. The present investigation was conducted to evaluate the effect of topical nimodipine (0.5%) drop on IOP of both normotensive and induced -hypertensive eyes in rabbits. Thirty six rabbits were included in the present study .Two groups (each group contains 6 rabbits) were used to evaluate the effect of nimodipine, one as a normotensive group and the other for induction of hypertensive. Nimodipine ophthalmic solutions were instilled twice daily for 7 days in both normotensive and induced -hypertensive eyes (that induced by weakly subconjunctival injection of 0.7 ml of betamethasone suspension for 4 weeks). On the other hand another two groups were used to evaluate the effect of (twice daily instillation for 7 days) of Timolol and distilled water (DW). IOP measured by Schiotz tonometer daily at about the same time (9.0 am) to avoid IOP diurnal fluctuation. The main findings of the present study were the followings: Nimodipine (0.5%) was very effective in lowering IOP in both normotensive and ocular hypertensive rabbits. Mean IOP decreased after one day of nimodipine instillation by (1.5 ± 0.43 mmHg) in normotensive eyes and by (4.5± 1.45 mmHg) in hypertensive eyes. A significant results (P ≤ 0.05) were obtained when compared the results of nimodipine with DW (as a negative control group), on the other hand no significant differences were obtained when compared with that of Timolol (as a positive group). The results obtained in this study provide experimental evidences for the effectiveness of nimodipine (0.5%) ophthalmic solutions in the reduction of IOP. In addition to above nimodipine in applied doses were found to have tolerable ocular hypotensive effect.