Effects of triamterene on serum and skeletal muscle electrolytes in diuretic-treated patients.

The effects on plasma and skeletal muscle electrolytes of the combination of triamterene 37.5 mg and hydrochlorothiazide 25 mg daily were studied in 19 patients on prior long-term (greater than 1 year) diuretic therapy for arterial hypertension and/or congestive heart failure. A further 20 patients fulfilling the same admission criteria were used as controls. Blood samples and skeletal muscle biopsies were taken before the study and after 6 months on therapy. The diuretic-treated group had a significant increase in skeletal muscle potassium and magnesium after 6 months on therapy as compared to the controls. Thus, the combination of triamterene and hydrochlorothiazide appeared effective in preserving the cellular content of potassium and magnesium on a long-term basis in the type of patient studied.