Kiyoharu Takikawa

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

Abstract The effect of the administration of a cardiovascular Ca2+-antagonist (nifedipine) on arterial blood pressure, heart rate, and plasma renin activity was investigated. Blood pressure of normotensive healthy volunteers (n = 4) does not change significantly by administration of 10 mg. (from 119 78 to 120 75 mm. Hg ) and 30 mg. (from 114 69 to 105 66 mm. Hg ) of nifedipine. When nifedipine (30 mg.) is administered with propranolol (beta-blockade), a slight decrease of systolic and diastolic blood pressure was observed (from 119 73 to 104 67 mm. Hg ). Blood pressure of hypertensive patients is significantly lowered by 10 mg. of nifedipine from 172.9 to 130.3 mm. Hg (25 per cent reduction) systolic, and from 112.9 to 86.6 mm. Hg (23 per cent) diastolic (n = 7). Thirty mg. nifedipine had a slightly stronger hypotensive effect, namely 27 per cent reduction in systolic and 28 per cent in diastolic values (n = 9). Combined administration of nifedipine and propranolol, resulted in lowering initial blood pressure by 32 per cent and 30 per cent reduction in systolic and diastolic (n = 8), respectively. The heart rate of normotensive patients hardly changes with administration of 10 and 30 mg. of nifedipine and combined medication. But in hypertensive subjects it is significantly increased by nifedipine; from 66.3 to 80.3 (p Plasma renin activity of normotensive and hypertensive subjects is increased by 30 mg. of nifedipine. Combined administration of nifedipine and propranolol decreases plasma renin activity in both normotensive and hypertensive patients. The antihypertensive effect of nifedipine is enhanced and prolonged by propranolol. The observed increase in heart rate and plasma renin activity with nifedipine is inhibited by propranolol, probably by inhibiting the cardiovascular effects of the activity of the sympathetic nervous system. The results of this study indicate that oral administration of nifedipine is very effective in lowering arterial blood pressure in hypertensive patients, especially when combined with propranolol. Administration of nifedipine with beta-blockade resulted in satisfactory management of hypertension with minimal adverse drug reactions which could be possibly attributed to the preparation, especially in the management of hypertensive emergencies including hypertension associated with acute myocardial infarction and coronary insufficiency.