Triamterene (2, 4, 7-triamino-6-phenyl pteridine, Dytac - SKF) is a new oral diuretic. It increases the urinary excretion of sodium, chloride and bicarbonate, but decreases the urinary loss of potassium. The diuretic effect of triamterene depends neither on carbonic anhydrase nor on antagonism of aldosterone, but appears to be due to a direct action of the drug on the distal renal tubule, reducing the reabsorption of sodium.