Amlodipine vs Nifedipine. A crossover study of efficacy and tolerability in patients with stable angina pectoris

A randomised crossover study was conducted to compare the efficacy and tolerability of amlodipine with that of slow release nifedipine in patients with stable exertional angina. After a 1-week drug washout phase, 48 patients were treated for 4 weeks with amlodipine (5 to 10 mg once daily) or slow release nifedipine (20 to 40 mg twice daily) and then crossed over to the alternative regimen; dosages were titrated to response within the dose range allowed. Both drugs were effective in controlling cardiac ischaemia, as evidenced by a reduced incidence of anginal episodes (reported by patients and observed with Holter monitoring) and increased exercise tolerance. From the results of bicycle stress tests, both drugs appeared to reduce myocardial oxygen consumption during dynamic exercise by limiting the increase in heart rate; these findings were also confirmed by heart rate and systolic blood pressure determinations. Patients who received amlodipine during the second treatment phase showed arterial pressures similar to those achieved with slow release nifedipine, but heart rates were lower. In contrast, patients treated with amlodipine during the first phase experienced a further reduction in blood pressure and an increase in heart rate when subsequently treated with nifedipine; however, these results require additional confirmation. The incidence of adverse events was also lower during treatment with amlodipine than with nifedipine. In conclusion, amlodipine has an efficacy and tolerability profile that is at least as good as that of slow release nifedipine in the treatment of patients with stable angina pectoris.