Antihypertensive effect of cardiovascular Ca2+-antagonist in hypertensive patients in the absence and presence of beta-adrenergic blockade

Different antihypertensive effects of nifedipine in conscious experimental hypertensive and normotensive rats

Antihypertensive effects of nifedipine and hydralazine were investigated in normotensive rats, spontaneously hypertensive rats (SHR), DOCA-NaCl hypertensive rats and renal hypertensive rats all in a conscious state. The blood pressure fall after nifedipine 5 mg/kg p.o. was 22% of the initial value in normotensive rats, 49% in SHR, 53% in DOCA-NaCl hypertensive rats and 44% in renal hypertensive rats. Hydralazine in the same dose decreased the blood pressure by 40% in normotensive rats, 52% in SHR, 33% in DOCA-NaCl hypertensive rats and 54% in renal hypertensive rats. The selective action of nifedipine in hypertensive rats in contrast to normotensive rats seemed to be attributable to the different affinity for calcium ion of vascular smooth muscle of hypertensive rats as compared with that of normotensive rats. Also, the heart rate of hypertensive rats or normotensive rats was increased with nifedipine but less than with hydralazine.

Antihypertensive effect of fractionated sublingual administration of nifedipine in moderate essential hypertension

The magnitude and duration of the antihypertensive effect of nifedipine were studied in 7 cases of moderate essential hypertension. In a double-blind crossover study, nifedipine 10 mg or a placebo were administered sublingually 4 times a day for 2 days, and the results were compared. Each dose of nifedipine reduced systolic and diastolic blood pressure by 14% both in the supine and upright positions. The antihypertensive action lasted for about 3 h and it was not cumulative. The reduction in blood pressure was associated with a temporary increase in heart rate. Administration of nifedipine 10 mg did not significantly raise plasma renin activity or plasma aldosterone. The drug was well tolerated and no side effects were detected.

Antianginal efficiency of nifedipine with and without a beta-blocker, studied with exercise test. A double-blind, randomized subacute study

Twenty-one patients, mean age 60.3 years, with stable angina pectoris earlier treated with beta-blockers, were investigated with standardized exercise tests to evaluate the action of nifedipine alone and in combination with a beta-blocker. The first exercise test was performed 3 weeks after treatment with the patient's usual beta-blocker. Following this, the patients were tested twice after a double-blind cross-over 3-week trial with nifedipine and placebo. The patients were subsequently treated for 3 weeks with nifedipine 10 mg 3 times daily or placebo and then performed an exercise test. During the 4th period of 3 weeks the patients took a combination of nifedipine, 10 mg 3 times daily, and their usual beta-blocker and then performed the final exercise test. Nifedipine alone raised the heart rate by 5 beats/min at rest and diminished the systolic blood pressure at rest by 17 mm Hg. During exercise at comparable load the heart rate did not change significantly, but the systolic blood pressure decreased with 22 mm Hg. The exercise tolerance expressed as total work increased on a average by 20%, range-14 - + 194%. Nifedipine in combination with a beta-blocker gave a further decrease in the systolic blood pressure, totally 37 mm Hg at comparable load. The exercise tolerance increased more, totally by an average of 41%. There was a significant correlation between basal values for systolic blood pressure registered during the placebo period at rest and the percentage change in total work. The atrioventricular conduction time did not change significantly compared to placebo during treatment with nifedipine or the combination nifedipine + beta-blocker. No serious side-effects were observed during the study.