Effect of nifedipine and propranolol on blood flow, venous compliance and blood pressure in essential hypertension

To determine the efficacy of nifedipine combined with propranolol in the treatment of hypertension, 23 patients with essential hypertension uncontrolled while they were receiving propranolol, 120 mg/d, entered a dose response trial of four 8-week periods while continuing propranolol therapy. Therapy during the four periods consisted respectively of a placebo, 30 mg/d of nifedipine, 30 or 60 mg/d of nifedipine, and 30 or 60 mg/d of nifedipine along with only 60 mg/d of propranolol. Studies of forearm blood flow and venous compliance were carried out in nine of the patients. Ten patients dropped out after the first period. The mean blood pressures while the patients were recumbent after the first, second and third periods were 163 +/- 17/100 +/- 6, 147 +/- 13/89 +/- 10 and 141 +/- 19/84 +/- 10 mm Hg respectively. There was no evidence of tolerance in the four patients who received 30 mg/d of nifedipine during the third period. There was a significant dose-diastolic pressure response (p less than 0.0006) without a change in heart rate in the eight who received 60 mg/d of nifedipine during this period. After 16 weeks of therapy with nifedipine 11 patients had a diastolic pressure less than 90 mm Hg while recumbent. While mean blood pressure and heart rate for the group were not significantly increased at the end of the fourth period, in three of the patients the diastolic pressure while recumbent increased to over 90 mm Hg. This suggests that 120 mg/d of propranolol is the minimum dose required for concomitant therapy. Adverse symptoms were mild and transient. Forearm plethysmography showed that nifedipine induced arteriolar but not venous dilation and that propranolol attenuated the vasodilator effect of nifedipine. The author concludes that nifedipine was safe and effective in combination with propranolol in this group of patients with essential hypertension.