Long-term treatment with slow-release frusemide compared with thiazide treatment in arterial hypertension

The effect of 30 mg/day slow-release frusemide given orally for 12 months was studied in 64 patients previously treated with thiazides for mild to moderate essential hypertension. Frusemide had a significant antihypertensive effect (P less than 0.001), and compared to thiazides significantly reduced fasting serum glucose (P less than 0.015), haemoglobin A1c (P less than 0.025), albumin (P less than 0.025) and serum calcium (P less than 0.025), and significantly increased serum sodium and chloride concentrations (P less than 0.0001). There was also a non-significant trend for frusemide to reduce serum total cholesterol, triglycerides and urate, and to increase serum potassium. Frusemide was well tolerated in all but three patients. It is concluded that slow-release frusemide has a comparable antihypertensive effect to that of thiazide diuretics, but has fewer metabolic side-effects, and should be used in-preference to thiazides for the treatment of arterial hypertension when a diuretic is indicated.