Double-blind comparison of amlodipine and nifedipine retard in the treatment of mild to moderate hypertension.

The efficacy and safety profiles of amlodipine (5-10 mg once daily) and nifedipine retard (20-40 mg twice daily) were compared in 111 hypertensive patients (sitting DBP in 95-115 mmHg) during eight weeks of treatment in a randomised double-blind parallel group study. BP was measured 22-24 hours after the daily dose of amlodipine and 10-12 hours after a dose of nifedipine retard. Baseline sitting BPs of 175/105 mmHg and 168/104 mmHg were significantly reduced (P < 0.05) to 157/93 mmHg and 151/92 mmHg at the end of treatment in response to mean daily doses of amlodipine 7.3 mg and nifedipine retard 58.9 mg. There were no clinically significant changes in heart rate with either treatment. Three patients in the amlodipine group and five patients in the nifedipine retard group could not be considered in analysis. The total numbers of adverse events (considered related or possibly related to treatment) (42 vs. 36) as well as the numbers of patients experiencing such events (22 vs. 22) were similar in the amlodipine and nifedipine retard treated groups, respectively, but with a greater incidence of headaches in response to nifedipine retard and of oedema in response to amlodipine. Five patients in each treatment group discontinued therapy due to such events. Overall the results showed once daily amlodipine as equivalent to twice daily nifedipine retard in the management of mild to moderate hypertension.