Labetalol in the treatment of stable exertional angina pectoris: a comparison with nifedipine.

Labetalol, a combined alpha- and beta-receptor antagonist, was compared with nifedipine in a placebo-controlled, randomized double-blind cross over study (four week treatment periods) of 11 normotensive patients with stable exertional angina pectoris. Standard recommended doses of both drugs (labetalol 200-400 mg twice daily, nifedipine 10-20 mg three times daily) were used. Angina frequency was similar during the placebo washout period and treatment with the two drugs. The duration of treadmill exercise to angina, ischaemia (greater than 1 mm ST segment depression), and end of exercise was increased by both labetalol and nifedipine when compared with placebo, but there was no difference between the two drugs. Ambulatory ST segment monitoring demonstrated that the frequency, duration and magnitude of ST segment depression, whether painful or silent, were unaffected by either drug. Labetalol is an effective agent in improving exercise tolerance in normotensive patients with stable exertional angina pectoris, with an efficacy similar to that of nifedipine.