An open study to compare the efficacy and tolerability of two diuretic combinations, frusemide plus amiloride and hydrochlorothiazide plus amiloride, in patients with mild to moderate essential hypertension.

Forty-four patients with mild to moderate essential hypertension were entered in an open study to compare the efficacy and tolerability of the two diuretic combinations, frusemide (40 mg) plus amiloride (5 mg) and hydrochlorothiazide (50 mg) plus amiloride (5 mg), as first-line treatment. After a 2-week run-in period when no antihypertensive medication was given, patients were randomized to receive one or other combination at a dose of 1 tablet daily for 2 weeks. Patients either remained on this regimen for a further 8 weeks or, if their blood pressure was not controlled, dosage was increased to 2 tablets daily. In the latter case, patients were re-assessed after 2 weeks, and those who showed a positive response remained in the study for 8 additional weeks. In the 36 patients assessed (18 in each group), both treatments were found to reduce blood pressure effectively in a high percentage of patients treated. Hydrochlorothiazide/amiloride, however, caused a significant reduction in both plasma potassium and sodium levels whereas frusemide/amiloride did not. More adverse events were reported by patients taking frusemide/amiloride, but the majority of these were trivial.