Prazosin as initial antihypertensive therapy: correlates of sympathetic function.

Abnormal sympathetic function has been proposed as a factor in the development of essential hypertension. If this is the case, prazosin hydrochloride, which works by a selective, peripheral, antisympathetic effect--postsynaptic alpha blockade--may have an advantage over other antihypertensive agents. In this study, blood pressure response and measures of sympathetic and baroreflex function were followed in 13 hypertensive patients. Prazosin alone significantly reduced standing and sitting diastolic blood pressures without affecting pulse rates, plasma catecholamines or baroreflex slopes in all patients. The addition of a thiazide diuretic in persons who did not achieve goal blood pressure on prazosin alone was generally successful in reducing blood pressure to desired levels, and increased both plasma renin activity and aldosterone concentrations. No significant relation was apparent between specific characteristics of sympathetic function and response to prazosin as initial therapy, although patients responding tended to have initially higher plasma norepinephrine concentrations.