In a double-blind, randomised, parallel group study, 128 patients with sitting diastolic blood pressure between 95 and 125 mm Hg (Phase V) after 2-4 weeks run-in on placebo, received enalapril 10-40 mg once daily (65 patients) or nifedipine retard 10-40 mg twice daily (63 patients), utilising a double dummy technique. Dual target blood pressures were less than 150 mm Hg systolic and less than 90 mm Hg sitting diastolic. Inadequate responders had hydrochlorothiazide 12.5-50 mg once daily added. 2. The 3 h post-dose sitting blood pressures were lowered by 18/14 mm Hg (enalapril) and 20/14 mm Hg (nifedipine), but nifedipine gave greater standing reductions (16/13 mm Hg enalapril, 22/17 mm Hg nifedipine). The dual target blood pressures were achieved by 45% of those taking enalapril monotherapy and 43% of those taking nifedipine monotherapy. At the end of the hydrochlorothiazide phase the dual target pressures were achieved by 63% of the enalapril group and 56% of the nifedipine group. 3. Overall, 17 patients reported adverse events during the placebo run-in. During the active treatment-periods, 42 patients in the enalapril group experienced adverse events, as did 49 of those on nifedipine. Orthostatic effects were confined to those taking enalapril, whereas flushing/erythema, oedema and palpitations were more common in the nifedipine group. 4. Five patients in the enalapril and 14 in the nifedipine groups were withdrawn because of adverse events. One of those withdrawn on enalapril had angioneurotic oedema.(ABSTRACT TRUNCATED AT 250 WORDS)
