Clinical evaluation of amiloride, a potassium‐sparing diuretic

Amiloride (MK 870), a new potassium‐sparing diuretic belonging to the pyrazine carboxamide class was evaluated in 34 hospitalized patients with fluid retention. The drug increased the excretion of sodium, chloride, and water but decreased potassium excretion. The major natriuretic effects of the drug were complete within 24 hours but in a few patients some potassium‐sparing lasted longer. The therapeutic efficacy of amiloride was compared with that of triamterene at ceiling dosages selected from the early portion of the dose‐response plateaus of the 2 drugs. The natriuretic and potassium‐sparing efficacies of 40 mg. amiloride were significantly greater than those of 200 mg. triamterene. At submaximal dosages, amiloride potentiated the natriuresis and reduced the potassium loss evoked by ethacrynic acid. The potassium‐retaining action of amiloride was apparent even in the presence of full doses of spironolactone.