[Effects of minoxidil on blood pressure and plasma volume in refractory hypertension (author's transl)]

We substituted minoxidil for dihydralazine in the treatment of 10 patients with refractory hypertension. Supine diastolic blood pressure decreased from 114 +/- 15 mmHg ou dihydralazine to 90 +/- 10 mmHg after one week on minoxidil (mean +/- ISD, p less than 0.01), the concomitant therapy being unchanged (sodium depletion and betablockade in all patients, methyl dopa or clonidine in seven). Simultaneously themean plasma volume increased by 395 ml (p less than 0.02) with no correlation to the decrease in blood pressure, and with no change in plasma renin activity and plasma aldosterone. Further expansion of plasma volume was prevented by furosemide, individual dosage requirement ranging from 40 to 500 mg/day, irrespective of the renal function. fter three to six months of ambulatory treatment a satisfactory blood pressure control was maintained. Hirsuties appeared in all our patients, but no subjective side effects was reported.