Urapidil. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in the treatment of hypertension.

Urapidil is a postsynaptic alpha 1-adrenoceptor antagonist with a pharmacodynamic profile similar to prazosin. Unlike prazosin, however, urapidil also has some central activity which may explain the apparent improved tolerability of urapidil, including the absence of first-dose syncope. In clinical trials urapidil therapy resulted in significant reductions in blood pressure in patients with mild to severe essential hypertension, with little influence on heart rate. It is an effective antihypertensive when administered as monotherapy or in combination with beta-blockers and thiazide diuretics. In the few patients with cardiac dysfunction who have been studied to date, urapidil has improved myocardial oxygen consumption, systemic vascular resistance, left ventricular function, cardiac output and pulmonary capillary wedge pressure; however, further study is needed to assess the full therapeutic potential of urapidil in these patients. Urapidil has also been used successfully in the treatment of hypertensive emergencies, including eclampsia and pre-eclampsia, hypertensive crisis and hypertension occurring during general and cardiac surgery, rapidly lowering blood pressure without altering heart rate. Urapidil does not affect lipid or glucose metabolism, nor does it impair renal function. In addition, urapidil may be beneficial to patients with pulmonary hypertension, in whom it dilates pulmonary vascular beds to a greater extent than systemic vasculature, although therapeutic trials have not examined this effect. The most common adverse effects associated with urapidil therapy are dizziness, nausea, headache, fatigue and palpitations; however, these tend to be mild and transient and usually do not require discontinuation of treatment. Thus, urapidil offers a useful alternative to currently available drugs for the treatment of mild to severe hypertension, either as monotherapy or in combination with other antihypertensive drugs.