Felodipine in hypertension.

Felodipine, a selective arteriolar dilator, was given to 13 hypertensive patients to assess its hypotensive effects and duration of action. Nine patients were treated with 5 mg three times a day and 4 with 10 mg three times a day. Mean blood pressures fell with both treatment regimens: 5 mg placebo 170/103 mmHg; 5 mg felodipine 148/91 mmHg; 10 mg placebo 154/93 mmHg; 10 mg felodipine 137/82 mmHg. Heart rates increased as blood pressures fell with both treatments. However, in the patients given 5 mg three times a day this effect was less noticeable after successive doses. Plasma concentrations of noradrenaline, both resting and tilted, increased after felodipine. There was a negative correlation between the fall in blood pressure and the increase in noradrenaline, suggesting that those patients with good baroreceptor reflexes were better able to counteract the effects of vasodilatation. Four of the nine patients treated with 5 mg felodipine three times a day experienced mild and transient adverse effects. Of the four patients treated with 10 mg three times a day, three experienced moderate to severe headache, and for this reason recruitment into this group was stopped. Felodipine at a divided daily dose of 15 mg effectively lowered blood pressure.