Short-term effects of felodipine, a new dihydropyridine, in hypertension

Felodipine, a dihydropyridine, is a new vasodilating calcium antagonist which lowers blood pressure (BP) by selective action on vascular smooth muscle, especially in the resistance vessels. The effects on BP, heart rate (HR) and tolerance of different single oral doses of felodipine were studied in two series of hypertensive patients. When felodipine was given as single drug to 14 previously untreated hypertensives in a single-blind manner, BP was rapidly reduced by about 15% while HR increased by 25%. Felodipine given in a double-blind manner to eight patients on chronic beta-adrenoceptor blockade reduced BP by some 15-20% compared to placebo, while HR did not change. There was a significant correlation between the pre-treatment mean arterial BP (MAP) and the maximal relative change in MAP, i.e. the higher the initial BP the greater the reduction after felodipine. A significant correlation was also found between the plasma concentration of felodipine and the relative change in MAP. Felodipine was generally well tolerated. When given alone felodipine caused the side effects expected from a pure vasodilator, i.e. headache, flushing and palpitations. When given together with a beta-adrenoceptor blocker, the side effects were much less apparent.