Hyponatraemia in congestive heart failure during treatment with captopril.

Hyponatraemia in congestive heart failure during treatment with captoprilThe oral converting-enzyme inhibitor captopril shows promise in the treatment of cardiac failure.We used the drug in five patients with congestive heart failure that had proved unresponsive to conventional treatment and observed a clear-cut fall in plasma sodium concentration. Methods and resultsWe studied five men aged 54-72 years with congestive heart failure (New York Heart Association functional class III or IV) secondary to coronary artery disease.All had previously received conventional medications, including vasodilators, without success.Throughout the seven-day study they received a constant dietary intake of sodium (33-48 mmol(mEq)/day) and potassium (73-100 mmol(mEq)/day; body posture was restricted to the supine and sitting positions in bed; and their regular doses of digoxin (62-5-250 ,ug/day) and frusemide (80-500 mg/day) were continued.All other drugs were stopped at least five days before the study.After a two-day run-in period captopril was administered by mouth in an eight-hourly incremental regimen (6-25-150 mg/dose), and blood was drawn one hour after each dose increase for measurement of plasma electrolyte and hormone concentrations.