Hormonal and blood pressure responses to tilting in beta-blocked essential hypertension treated with felodipine or prazosin.

A study was carried out of 22 patients with essential hypertension who were treated with metoprolol (100 mg/day) and placebo for 4 weeks. Felodipine (n = 11) or prazosin (n = 11) were then added in increasing doses (felodipine 5, 10, 20 mg bid; prazosin 1, 2, 4 mg bid) for 2 weeks until a diastolic blood pressure of less than or equal to 90 mm Hg was achieved. Acute haemodynamic and hormonal responses to 80 degrees tilting (measurements after 4 minutes' tilt) were obtained immediately prior to randomisation to felodipine or prazosin, and after 6 to 8 weeks of treatment. At randomisation, 80 degrees tilt produced no change in blood pressure and only a small increase in pulse rate. There was no significant change in the plasma renin-angiotensin system, vasopressin or adrenaline concentrations. Plasma noradrenaline concentration rose in response to 80 degrees tilt. Following substitution of felodipine (n = 11) or prazosin (n = 11) for placebo, and continuation of metoprolol, blood pressure fell. 80 degrees tilt caused no change in the plasma renin-angiotensin system, vasopressin or adrenaline concentration. Plasma noradrenaline concentration rose in response to tilt, as before. Felodipine is an effective antihypertensive agent when used with metoprolol.(ABSTRACT TRUNCATED AT 250 WORDS)