Calcium antagonists: a review of the recent comparative trials

A review of published studies was undertaken to assess the efficacy and patient tolerability of calcium antagonists compared with established antihypertensive therapy, i.e. beta-blockers and diuretics. Randomized controlled trials undertaken in Caucasian patients with mild to moderate hypertension were evaluated. Only 12 trials fulfilled the criteria for inclusion in the review and they differed considerably with regard to design, method of analysis, and drug and dose regimen used; a formal pooled analysis of the data was not feasible. Few trials demonstrated significant differences in blood pressure control between treatments. Side effects were rarely seen, or were not assessed, and the number of patients studied was relatively small. Two large unpublished trials have recently evaluated the slow-release twice-daily formulation of 20 mg nifedipine, 50 mg atenolol and the fixed combination of 50 mg atenolol + 20 mg nifedipine, using a randomized double-blind crossover design. Mean blood pressure with atenolol was consistently lower than with nifedipine although this achieved statistical significance in only one study (P less than 0.01). Fixed combination therapy gave a greater antihypertensive effect than either atenolol or nifedipine administered alone (P less than 0.05 to P less than 0.001). Side effects were most common with nifedipine treatment, less common with combination therapy and occurred least commonly with atenolol alone (P less than 0.001). In one study involving 44 patients (aged 20-70 years), side effects attributable to peripheral vasodilation secondary to nifedipine therapy, e.g. flushing and sweats, were significantly greater (P less than 0.05) with nifedipine (n = 11) than with atenolol (n = 3).(ABSTRACT TRUNCATED AT 250 WORDS)