Overview of clinical trials with urapidil

Urapidil has been approved as sustained-release capsules containing 30, 60 and 90 mg, respectively, and as ampules containing 25 and 50 mg for treatment of all grades of hypertension, in several countries in Europe, South America, as well as in Japan and other Asian regions. In general, the treatment should start with 60 mg twice daily, 1 capsule in the morning and 1 in the evening. This schedule may be adapted according to the therapeutic needs. During the last few years, urapidil has been investigated extensively in comparison with several types of established antihypertensive drugs. Urapidil given orally has been tested in comparative trials against placebo, acebutolol, metoprolol, captopril, nifedipine and nitrendipine with responder rates of 40 to 70%. These responder rates are to be expected for a variety of antihypertensive drugs in monotherapy. Further studies with clonidine, prazosin and alpha-methyldopa showed similar responder rates as established for the other antihypertensive drugs studied. Adverse reactions include dizziness, headache and nausea and occasionally tiredness, orthostatic dysregulation and gastric disorders. These symptoms were transient, mostly occurring during the early phases of therapy and disappearing as treatment continued. Adverse effects are considered to be mainly due to blood pressure reduction. Intravenous comparative trials have been performed with urapidil against placebo, diazoxide and sodium nitroprusside. Adverse effects of parenterally applied urapidil are similar to those observed during oral treatment. Specific contraindications for urapidil are unknown. However, as for other vasodilating drugs, intravenous urapidil should not be administered to patients with stenosis of the aortic isthmus or with aortic valve insufficiency.