Nifedipine and propranolol: a beneficial drug interaction

The antianginal effects of two active drugs, nifedipine and propranolol, alone in combination, were compared with those of placebo in a double-blind clinical trial that included 16 patients with chronic stable angina triggered by exertion. A low dose and a high dose of the active drugs were used (nifedipine, 30 and 60 mg/day; propranolol, 240 and 280 mg/day). Precordial exercise mapping and continuous electrocardiographic recordings were used to assess objective response to therapy, and the patients were asked to keep a diary of episodes of chest pain and consumption of nitroglycerin tablets for subjective appraisal. Both frequency of chest pain and nitroglycerin consumption were significantly reduced by each of the active drugs when compared with placebo, and the combination of nifedipine and propranolol added significantly to the effectiveness. Reductions in area of ischemia and number of episodes of ST segment depression on 48-hour ambulatory electrocardiographic monitoring corroborated the efficacy of each active treatment with respect to placebo. Nearly 60 percent of all episodes of ST segment depression were painless and responded to the active treatment in the same manner as did the episodes associated with chest pain. Side effects were mild and all treatments were well tolerated. The objective methods used allowed for clear-cut differentiation of treatment effects with the various regimens. Although the two drugs alone were significantly more effective than placebo, their combination provided an even greater improvement (p less than 0.005), and therefore it appears to be a safe and effective form of treatment for chronic stable angina.