Antihypertensive and humoral effects of nifedipine in essential hypertension uncontrolled by hydrochlorothiazide alone.

This double-blind placebo controlled study investigated the antihypertensive and humoral effects of nifedipine capsules in patients with essential hypertension inadequately controlled (seated diastolic blood pressure greater than or equal to 95 mm Hg) by hydrochlorothiazide (HCTZ) alone. Nifedipine acutely (first dose) lowered supine blood pressure but did not change supine plasma renin activity (PRA) or aldosterone concentration. In contrast to placebo, short-term treatment (10 weeks) with nifedipine (n = 9, mean dose 43 +/- 16 mg daily) added to HCTZ (50 mg daily) significantly decreased seated blood pressure by 8.6 +/- 10.8/11.5 +/- 6.9 mm Hg. Neither nifedipine or placebo therapy altered PRA, plasma aldosterone concentration or 24 hour urinary aldosterone excretion. Nifedipine frequently caused mild vasodilator symptoms but these did not limit therapy in most patients. There was no correlation between PRA, plasma aldosterone concentration or 24 hour urinary aldosterone excretion and the acute or short-term blood pressure response to nifedipine in these diuretic treated patients. The acute blood pressure response to nifedipine did not predict short-term efficacy. Thus, nifedipine added to a diuretic is generally well-tolerated, effectively lowers blood pressure, and does not stimulate the renin-angiotensin-aldosterone (RAA) axis. Additionally, in diuretic treated patients, the activity of the RAA axis and initial blood pressure response to nifedipine are not predictive of short-term efficacy.