Comparison of nitroglycerin patches and nifedipine.

Fifteen patients with stable angina participated in a 12-week crossover study to evaluate the efficacy of nifedipine and nitroglycerin patches. There was an initial 2-week drug washout period followed by a 2-week control period when patients received no other antianginal treatment other than sublingual nitroglycerin for relief of angina episodes. At the end of the 2-week control period, exercise performance was assessed with treadmill exercise testing and measurement of oxygen consumption during the final third of the dosing interval. Myocardial perfusion was assessed using thallium scintigraphy with the injection of thallium at 85% of the maximum oxygen consumption. Patients were then randomized to nifedipine or nitroglycerin patches, and the dosage was titrated at weekly intervals according to symptomatic response. The final dose was received for at least 2 weeks. After 4 weeks, patients received the alternate medication. Maximal exercise testing and thallium scintigraphy were repeated after each drug period. Both nifedipine (mean dose, 70 mg/day) and nitroglycerin patches (mean dose, 16 cm/day) significantly reduced the frequency of angina and the consumption of sublingual nitroglycerin. Nifedipine decreased the reversible thallium defect score (49 +/- 29 vs. 28 +/- 26 U, p less than 0.01). Both drugs reduced electrocardiographic evidence of myocardial ischemia at submaximal exercise. Maximal oxygen consumption was not significantly increased by either drug when the test was done during the latter part of the dosing interval. The clinical implications of this study are that the dosage of nifedipine and nitrate patches, based on symptomatic criteria of angina frequency reduction, may not result in objective improvement in exercise performance.