Introduction:

Depression is a common co-morbid illness with a prevalence of 16-23% in patients suffering from cardiovascular diseases. Verapamil, a calcium channel blocker, is widely used in the treatment of various cardiovascular diseases and has been shown to possess antidepressant effects, however, information on its interaction with antidepressant drugs like fluvoxamine, venlafaxine and tianeptine is limited. Hence, the present study was conducted.

Method:

The study was carried out in albino mice in two phases. In phase I, antidepressant activity of verapamil, fluvoxamine, venlafaxine and tianeptine was confirmed after their single dose administration using forced swim test (FST) and tail suspension test (TST) and their minimum antidepressant doses were determined. In phase II, the interaction of verapamil with fluvoxamine, venlafaxine and tianeptine for antidepressant activity was studied by administering these drugs orally on daily basis for 28 days and performing FST & TST on 1st, 14th and 28th day.

Results:

In phase I, all the studied drugs demonstrated antidepressant activity in dose dependent manner in both FST and TST. Minimal antidepressant dose of verapamil, fluvoxamine, venlafaxine and tianeptine was observed as 40, 25, 25 and 10 mg/kg respectively. In phase II, combinations of sub-antidepressant dose of verapamil (20 mg/kg) with sub-antidepressant doses of fluvoxamine (12.5 mg/kg), venlafaxine (12.5 mg/kg) and tianeptine (5 mg/kg) demonstrated additive antidepressant activity when compared to the control group and individual drug groups after same duration of treatment.

Conclusion:

Verapamil exerts dose dependent as well as treatment duration dependent antidepressant activity which is additive to antidepressant activity of fluvoxamine, venlafaxine and tianeptine.