Randomized double-blind comparison of side effects of nicardipine and nifedipine in angina pectoris. The Nicardipine Investigators Group.

Nicardipine and nifedipine are structurally similar dihydropyridine calcium channel blockers with demonstrated efficacy in the treatment of stable angina pectoris. The present study was a prospective randomized trial designed to evaluate the relative incidence of dizziness, flushing, headache, pedal edema, and palpitations during use of these drugs in patients with angina pectoris. Of 250 patients who entered into the comparative treatment part of the study, 140 patients were susceptible to developing symptoms to nifedipine as identified during a 1-month open-label treatment with nifedipine. These patients were compared with a parallel cohort of 110 patients, who were identified during the same open-label period, but remained mostly asymptomatic. After a 1-week washout of nifedipine, equal numbers of patients in each cohort began an 8-week period of randomized, double-blind treatment with nifedipine (20 mg three times daily) or nicardipine (30 mg three times daily). Patients who experienced these symptoms during the open-label nifedipine treatment had a higher incidence of the same symptoms during the blinded treatment regimen. Nicardipine-treated patients had a lower incidence of each of the symptoms than did the nifedipine-treated patients. Statistically significant differences were reported for dizziness, the most common of the side effects. Patients who were free of these symptoms in the open-label period usually remained free of them in the blinded comparison. However, even among those free of dizziness during the open-label nifedipine treatment, more patients reported experiencing dizziness in the blinded phase from nifedipine than from nicardipine (18% vs 6%; p = 0.02).