Effect of Flunarizine on Blood Glucose Levels in Normal Albino Rats Through Oral Glucose Tolerance Test

Background: Flunarizine is commonly used for migraine prophylaxis. It is a calcium channel blocker which blocks the L-type, T-type and N-type of calcium channels of pancreatic beta cells and other cells. It is believed to cause alterations in blood glucose levels secondary to its effect on calcium channel dependent insulin secretion. Objective: To evaluate the effect of flunarizine on blood glucose levels in normal albino rats through oral glucose tolerance test (OGTT) Materials and Methods: Flunarizine and distilled water were given orally for 5 days to the test (T) and control (C) groups of 6 normal albino rats respectively (N = 6). OGTT was conducted on both the groups on the 5^th day and blood glucose levels were analyzed at 0, 60 and 150 minutes. Data was analyzed with one way ANOVA and independent samples t -test. Results: Flunarizine caused hyperglycemia at all durations of the OGTT with a maximum difference of 26% at 0 hour. The extent of worsening was maximum at 60 - 0 minute interval in both the instances i.e. test group value compared with control (T-C) and control values compared with itself (C-C). The comparison of extent of hyperglycemia revealed that T-C showed 17% (47mg/dl) more hyperglycemia than the C-C (40 mg/dl). Conclusion: Flunarizine has hyperglycemic effects in normal albino rats when given for 5 consecutive days orally even at the dose used for prophylaxis of migraine in human beings. A word of caution is thus advised when using flunarizine in impaired glucose tolerance or diabetic subjects.