Single and divided daily dose piretanide in the treatment of uncomplicated essential hypertension: a double-blind comparison with a combination of hydrochlorothiazide and amiloride.

In a randomised double blind study in patients with mild to moderate hypertension, piretanide 6 mg once and twice daily significantly reduced both supine and erect blood pressure. This was seen after only 2 weeks and a further progressive reduction was evident over the ensuing 12-week trial period. The higher dose produced a mean maximal fall of 29% in supine diastolic pressure, compared with 23% after the lower dose; the difference is not significant. Hydrochlorothiazide 50 mg/amiloride 5 mg twice daily (HCT/A) also reduced supine blood pressure significantly after 2 weeks, but the reduction in erect diastolic blood pressure did not achieve statistical significance until 8 weeks. The maximal effect (a 13% fall in supine diastolic blood pressure) was significantly less than that of either piretanide regimen. Blood pressures in this group also returned more rapidly to pretreatment levels during the placebo washout phase at the end of the study. HCT/A produced a significant sustained rise in serum potassium and a reduction in serum sodium and chloride. Piretanide had minimal effects on serum electrolytes.