Effect of diuretic, beta-adrenoceptor blocking agent and their combination on elevated blood pressure and serum potassium: a cross-over study.

1. The antihypertensive effect of a new beta-adrenoceptor blocking agent, trimepranol (10--14 mg/twice daily), chlorthalidone (50 mg every second day) and their combination was studied in eighteen patients with mild to moderate essential hypertension. In a controlled randomized cross-over study the drugs were given for 6 week periods. 2. A significant and equal decrease in blood pressure was achieved both with trimepranol and chlorthalidone, whereas their combination was significantly more effective. 3. Trimepranol significantly antagonized the chlorthalidone-induced hypokalemia. 4. The results favor the use of diuretic or diuretic-beta-adrenoceptor blocker combination over beta-adrenoceptor blocker monotherapy in the treatment of mild to moderate hypertension.