EFFECT OF BUNAZOSIN AND ATENOLOL ON GLUCOSE-METABOLISM IN OBESE, NONDIABETIC - PATIENTS WITH PRIMARY HYPERTENSION

Antihypertensive drugs, recommended by the World Health Organization f or use in monotherapy, exert different effects on glucose and lipid me tabolism. In our study we compared the effects of the beta-blocker ate nolol (AT) and the alpha(1)-blocker bunazosin (BU) on glucose metaboli sm. The doses administered were chosen to produce similar antihyperten sive effects with both drugs. The study was conducted as a bicenter, p arallel, controlled, and double-blind study. All patients suffered fro m mild to moderate primary hypertension, were obese (body mass index > 26 kg/m(2)), but were nondiabetic. After a drug-free period of 4 weeks , patients were treated either with 6 and 12 mg of bunazosin (n = 15) or with 50 and 100 mg of atenolol (n = 17) once daily for 12 weeks. Gl ucose metabolism was measured by the iv glucose tolerance test (GTT) a nd the euglycemic hyperinsulinemic clamp test. The results show a simi lar blood pressure reduction with both drugs. However, their effects o n glucose metabolism were significantly (p < 0.05) different: The area under the curve (AUC) of glucose in the iv GTT increased 26.8% during atenolol treatment but decreased 30% during bunazosin treatment. The same influence on the AUC of insulin was observed [AT +-478.5 +/- 441. 8 (+22%) vs. BU, -588.5 +/- 411.1 (-22%)]. Similar changes were found in the glucose clamp test. The metabolic clearance rate increased 11.4 % during bunazosin use and decreased 8.4% during atenolol nse to the s ame degree that the insulin sensitivity index changed (BU +13.2% vs. A T -21.9%). The differences between the two treatment regimes were stat istically significant (p < 0.05). These results in obese hypertensives confirm the well-known negative effects of beta-blockers on glucose m etabolism. Additionally, they demonstrate that an alpha(1)-blocker suc h as bunazosin develops the same blood pressure-lowering effect as bet ablockers, but with a significantly better profile with regard to gluc ose metabolism. Therefore, the use of alpha(1)-blockers can be recomme nded for obese hypertensives without any special care for glucose meta bolism.