Determination of Antialdosterone Activity in Normal Dogs

Summary A method is described for detecting an aldosterone antagonist over a 6-hour period in the unanesthetized intact dog. The method is based upon the ability of an aldosterone antagonist to overcome the depressed urinary Na/K ratio caused by administration of the potent mineralocorticoid 9 α-fluorohydrocortisone. Using this procedure, it was shown that spironolactone-A is active at an oral dose as low as 3 mg/kg, and at 12 mg/kg has a significant natriuretic effect.