Comparison of the efficacy and safety of nifedipine coat-core versus amlodipine in the treatment of patients with mild-to-moderate essential hypertension. Hypertension Study Group.

The antihypertensive efficacy and safety of once-daily nifedipine coat-core was compared with that of once-daily amlodipine in a multicenter, prospective, double-blind, randomized, parallel-group study in which titration was based on response. The study consisted of a 2-week, single-blind, placebo run-in period followed by an 8-week double-blind treatment period. Double-blind treatment began with nifedipine coat-core 30 mg or amlodipine 5 mg. After 4 weeks of double-blind therapy, patients with a trough seated diastolic blood pressure (DBP) > or = 90 mm Hg received an increased dose of nifedipine coat-core (60 mg) or amlodipine (10 mg). A total of 207 patients received the study medication at 12 private-practice medical centers. Ambulatory blood pressure monitoring (ABPM) was performed at six medical centers with 38 nifedipine coat-core and 37 amlodipine patients. Data from 176 patients were valid for the primary efficacy analysis. Treatment groups were well matched with respect to baseline demographic and disease characteristics. During the study period, 59 (65.6%) nifedipine coat-core patients remained on their original 30-mg dose of study medication compared with 52 (60.5%) amlodipine patients who remained on the 5-mg starting dose. Mean trough blood pressure at baseline was 160.9/101.9 mm Hg in the nifedipine coat-core patients compared with 160.5/101.8 mm Hg in the amlodipine patients. Mean trough blood pressures at end point were 141.3/85.5 mm Hg and 140.7/85.9 mm Hg in the nifedipine coat-core and amlodipine groups, respectively. Equivalence between the two treatment groups was demonstrated based on the difference between amlodipine and nifedipine coat-core in the change from baseline in trough seated DBP (90% confidence interval, -0.50 to 2.59). Systolic blood pressure and 24-hour ABPM data supported the equivalent antihypertensive efficacy of the two treatments. Both drugs were well tolerated and had similar safety profiles. Nineteen patients in the amlodipine group experienced at least one adverse event compared with 12 in the nifedipine coat-core group. The amlodipine patients tended toward a later occurrence of adverse events plus a greater number of events, particularly edema and gastrointestinal symptoms. More patients in the nifedipine coat-core group (n = 3) than in the amlodipine group (n = 1) discontinued treatment because of adverse events.(ABSTRACT TRUNCATED AT 400 WORDS)