Bromocriptine, a Dopamine (D 2 ) Receptor Agonist, Used Alone and in Combination with Glipizide in Sub–Therapeutic Doses to Ameliorate Hyperglycaemia

Abstract

Bromocriptine, an ergot derivative, is an agonist at the dopamine 2 receptor and a sympatholytic. It is a well established drug in Parkinsonism, hyperprolactinaemia and acromegaly and it has various other clinical indications like induction of ovulation in female infertility. Bromocriptine has been evaluated in alloxan induced diabetic rats for its anti-hyperglycaemic effect with and without simultaneous use of glipizide. Diabetes was induced in albino rats by giving a single subcutaneous injection of alloxan in a dose of 150 mg/kg body weight. After 72 hours of giving alloxan injection, depending upon their blood glucose levels (350mg/dl and above), the rats were included into the study and they were divided into four groups, each comprising of 6 rats (n=24): Group 1 which was taken as control was given distilled water. Group 2 was treated with glipizide, a standard drug. Group 3 was treated with the test drug, bromocriptine and Group 4 was treated with sub therapeutic doses of test and standard drugs. The drugs were given to the diabetic rats once daily by oral route for 30 consecutive days, in order to assess their effects in terms of reduction in blood glucose levels. Blood glucose was estimated on 0(th), 10(th), 20(th), and 30(th) days of the study at fixed time intervals. Bromocriptine, which was used alone, lowered the blood glucose levels appreciably; whereas the concomitant administration of bromocriptine and glipizide in sub therapeutic doses produced a much more appreciable reduction. The results which were obtained in the group which received simultaneous administration of test and standard drugs in sub therapeutic doses were comparable to those of the group which received reference drug, glipizide. Hence, it can be concluded that bromocriptine may serve as a valuable adjunct to available anti-diabetic medication.