Effects of furosemide and chlorothiazide on blood pressure and plasma renin activity.

Short (2 weeks) and long (12 weeks) term effects of furosemide and chlorothiazide on blood pressure, plasma renin activity, and uric acid concentration were studied in 69 hypertensive patients. Both treatments caused significant reductions in blood pressure and increases in plasma renin activity and uric acid at 2 and 12 weeks in 6) normal renin patients; there was no difference between the effects of furosemide and that of chlorothiazide. Reduction in blood pressure in eight low renin patients who showed smaller changes in plasma renin activity and uric acid was not significant at 2 weeks but significant after 12 weeks of treatment.