KEY POINTS AND PRACTICAL RECOMMENDATIONS: • Hydralazine and
minoxidil act by dilating resistance arterioles, thus reducing peripheral resistance, with no dilating effect on the venous side of the circulation. • There is a baroreflex-mediated venoconstriction, resulting in an increase in venous return to the heart, along with a direct
catecholamine-mediated positive inotropic and chronotropic stimulation of the heart. • Hydralazine
therapy is usually combined with a sympathetic inhibitor to prevent expression of this reflex, as well as with a
diuretic agent to prevent
sodium retention caused by reduction in renal perfusion pressure. • Hydralazine is indicated in the long-term
therapy of
essential hypertension, in the short-term
therapy of
pregnancy-induced hypertension and
eclampsia, and in the
therapy of
hypertensive crisis. • Adverse effects include the anticipated
tachycardia, fluid retention, and
headache, caused by the vasodilation, especially in the early days of
therapy, but may frequently be prevented by the concomitant use of a β-blocker. • As with other drugs that are N-acetylated, there is a low risk of lupus-like syndrome with high doses and long-term use. • Because of the severity of adverse effects with
minoxidil, its usage is limited to persons with severe
hypertension unresponsive to other treatments. • Hirsutism, a common side effect of
minoxidil, is particularly bothersome in women and reverses in a few months after discontinuation. • Sodium
nitroprusside is used in the
intensive care setting to lower pressure in
hypertensive crisis or to treat severe left ventricular failure, particularly valuable when elevated pressure or severe left ventricular failure threatens the patient's survival. • Although
nitrates have not achieved widespread use as
antihypertensive agents, they are effective in producing sustained blood pressure (BP) reductions when added to other
antihypertensive regimens.