A randomised double-blind crossover study of isosorbide mononitrate and nifedipine retard in chronic stable angina.

In order to evaluate and compare the efficacy and safety of nifedipine retard and isosorbide-5-mononitrate as monotherapy in the treatment of stable angina, 18 patients with abnormal exercise electrocardiograms and angiographically proven coronary arterial disease were studied in a randomised placebo controlled double-blind crossover study comparing isosorbide 20 mg twice a day, sustained released isosorbide 40 mg once daily and nifedipine 20 mg twice a day each given for two weeks. Patients were assessed subjectively by counting the frequency of anginal attacks and glyceryl trinitrate consumed and objectively by maximal symptom-limited treadmill stress tests performed at "trough" therapeutic blood levels on the last day of each treatment period. There were no significant differences in all parameters between entry and run-out placebo. Compared to placebo, all three active treatments showed significant improvement in exercise time to 1 mm ST segment depression, amount of maximum ST segment depression and exercise duration. All three active treatments also significantly reduced the consumption of glyceryl trinitrate and frequency of anginal attacks. There were no significant differences between active treatments. Thus similar clinical improvements were produced by nifedipine retard and isosorbide, both being shown to be equally effective starting therapy for the treatment of patients with stable angina pectoris. Although anginal frequency was reduced by one third and exercise time increased residual symptoms and exercise ischaemia suggest that nifedipine retard and isosorbide may be more clinically useful in combination therapy. Neither demonstrated tolerance after two weeks of therapy.