Ocular Hypotensive Effect of Topical Verapamil and Diltiazem in Steroid Induced Glaucoma Model of Rabbits

Objectives: To evaluate possible ocular hypotensive effect of 0.5% diltiazem and 0.1% verapamil eye drops on intraocular pressure in steroid induced glaucoma model of rabbits. And compare with 0.5% timolol eye drops.
Methodology: Glaucoma was induced in rabbits (N=18) by bilateral topical instillation of 1% prednisolone eye drop (10 µl) twice a day for a period of 40 days. Before the induction of glaucoma, baseline intraocular pressure (IOP) in both the eyes of all rabbits was measured under sedation (i.v midazolam) by Schiotz tonometer. At the end of 40 days induced IOP was measured for all rabbits and rabbits were divided into three groups of six rabbits in each. Right eyes of group A, B and C rabbits received 0.5% diltiazem, 0.1% verapamil, and 0.5% timolol eye drops twice daily for 12 days respectively. Whereas, left eyes of all rabbits received distilled water hence represented as control. IOP was measured in all rabbits on every 4th day till 12 days of treatment period.
Results: Intra-group comparisons of IOP changes were made by paired‘t’ test. And unpaired‘t’ test for inter group comparisons. One way ANOVA was used for multiple group comparisons followed by post-hoc Tukey’s test for group wise comparisons. In 0.5% diltiazem treated eyes, the mean IOP significantly reduced from 22.9±1.9 mmHg (10%) on 4th day to 16.9±1.1 mmHg(S, P<.001) on 12th day (34%). Similarly, mean IOP in 0.1% verapamil treated eyes significantly reduced from 22.7±1.3 mmHg (7%) on 4th day to 15.5±1.4 mmHg(S, P<.001) on 12th day (37%). Whereas, mean IOP significantly reduced from 22.4±1.9 mmHg (14%) on 4th day to 16.4±1.4 mmHg (S, P=.001) on 12th day (36%) in 0.5% timolol treated eyes.
Conclusion: Topical 0.5% diltiazem and 0.1% verapamil significantly reduced the IOP in steroid induced glaucoma model of rabbits. However, Further research has to be carried out both in experimental and clinical subjects to reveal its efficacy and safety profile.