Double-blind placebo-controlled trial of terazosin effect on blood pressure and urinary output of dopamine in hypertensive patients

Abstract

In a parallel, double-blind study, 12 untreated hypertensive patients received terazosin (2-4 mg/day for 4 weeks), and 12 received placebo during the same period. Systolic and diastolic blood pressure decreased significantly in the terazosin group, from 150 +/- 5.0 mmHg systolic and 99.6 +/- 2.0 diastolic before treatment, to 134.0 +/- 7.0 systolic and 85.6 +/- 3.0 mmHg diastolic at week 4 of treatment. No significant blood pressure changes occurred in the placebo group. Blood pressure decrease showed a positive correlation (r = .62 and r = .52 for systolic and diastolic blood pressure, respectively) with the patient's age (P less than .05). Total plasma cholesterol decreased 18% in the terazosin group (P less than .05) and 9% in the placebo group (P greater than .05). Urinary dopamine excretion decreased significantly from 692.8 +/- 180.0 to 330.5 +/- 52.0 micrograms/24 hours in the terazosin group (P less than .05) and showed a nonsignificant increase in the placebo group. Compared with 22 age- and sex-matched healthy volunteers, urinary dopamine excretion in the hypertensive group before treatment was not statistically different (779.3 +/- 83.1 micrograms/24 hours). Dopamine excretion was higher in untreated hypertensive men and in male healthy volunteers compared with women. The decrease of urinary dopamine excretion observed under terazosin treatment could be due to a decrease of kidney dopamine synthesis or release induced by blood pressure reduction, or secondarily to the blockade of kidney alpha 1-receptors, modulating dopamine excretion. No significant changes were observed in urinary excretion of noradrenaline and adrenaline.