Antihypertensive and metabolic effects of increasing doses of atenolol and labetalol. A comparative study in primary hypertension

. Thirty–two patients with primary hypertension were studied in a double–blind crossover comparison between the cardioselective β1–blocking agent atenolol and the combined α–and β–blocking agent labetalol. The doses used were atenolol 50–150 mg twice daily and labetalol 200–600 mg twice daily. Both drugs effectively reduced blood pressure and heart rate. Dose increments every second week resulted in a higher proportion of patients with normal blood pressure (≤ 150/90 mm Hg) with both drugs. Labetalol was somewhat more effective in lowering upright blood pressure while atenolol caused a more pronounced heart–rate reduction. Both agents decreased plasma renin activity and urinary aldosterone excretion. Scalp tingling on labetalol (2 patients) and cold fingers with atenolol (1 patient) caused withdrawal of the drugs. Cold fingers were reported in another four patients during treatment with atenolol and in one when on labetalol. Tiredness and postural symptoms were more common during intake of labetalol.