Effects of spironolactone on serum and muscle electrolytes in patients on long-term diuretic therapy for congestive heart failure and/or arterial hypertension.

The effect of adding spironolactone (Aldactone) on muscle electrolytes was studied in 48 patients with arterial hypertension and/or congestive heart failure who had received conventional diuretic treatment, including a potassium supplement, for more than 1 year. After 6 months on spironolactone 100 mg/day as well as the original conventional diuretic therapy, there was a significant increase in both skeletal muscle potassium and magnesium. At the same time these parameters decreased in the control group. In the spironolactone group there was also a significant increase in the mean serum potassium and creatinine levels. There was a significant fall in blood pressure in the spironolactone-treated group.