Probable interaction between calcium entry blocker [Verapamil] and hypoglycaemic drugs in rats

Eighty albino rats of both sexes, weighing 250-300 g were used. Rats were divided into two groups each of 40, one of them as normal fasted and the other as alloxan diabetic one. Diabetic rats were obtained by subcutaneous injection of alloxan in a dose of 120 mg/kg body weight. The drug interaction between verapamil and three common oral hypoglycemic drugs were studied. Sulfonylurea drugs [tolbutamide and glibenclamide] and N,N-dimethyl guanyl-guanidine were used. Verapamil alone, increased blood sugar level in normal fasted and alloxan diabetic rats. Also, in combination verapamil interfere with the hypoglycemic effect of the before mentioned oral hypoglycemic drugs in normal fasted and alloxan diabetic rats. This result was explained as a result of interference with insulin secretion by blocking slow-inward conducting channels of Ca ++