[Comparison of oral diazoxide and minoxidil in refractory hypertension]

The efficacy and side effects of two potent vasodilatators, namely diazoxide and minoxidil given orally, were compared in 11 patients who had hypertension refractory to conventional drug treatment. The latter included diuretics, betablockers and/or sympatholytics, and either dihydralazine or prazosin. In a crossover approach, dihydralazine and prazosin were withdrawn and replaced by diazoxide or minoxidil. In nine patients the diazoxide phase preceded the minoxidil treatment, while in two it followed minoxidil treatment. Before introduction of the more potent vasodilators blood pressure averaged 181/107 mm Hg in the supine and 161/103 mm Hg in the upright position. Both, oral diazoxide (median dose 400 mg/d( and minoxidil (medium dose 17.5 mg/d) produced similar decreases (p < 0.02) in mean arterial pressure (-15%) in the supine and (-11 vs. -12%) in the upright position. They caused a comparable tendency for sodium retention and weight gain which could be satisfactorily controlled with increased diuretic therapy, except in one patient. Hypertrichosis occurred with both drugs, but tended to be somewhat milder with diazoxide. Electrocardiograms remained generally unchanged. Plasma glucose levels were increased during diazoxide treatment in six patients necessitating interruption of this therapy in four patients. It is concluded that the antihypertensive potency and most side effect of orally administered diazoxide are comparable to those of minoxidil, except for diazoxide-related hyperglycemia which may limit the use of this substance.