Renal clearance of canrenoate in normal man

Potassium canrenoate was administered intravenously, twice at a 9-hr interval, to 3 apparently healthy male volunteers. No consistent changes in endogenous creatinine or PAH clearances were observed for 6 hr after the initial 200-mg dose of this aldosterone antagonist. The clearance of canrenone (the major gamma-lactone metabolite) exceeded by 70% the simultaneous clearance of creatinine from the second through the sixth hour. The excretion of canrenone amounted to 6.8 mg (3.4%) of the dose during the 6-hr clearance study, but was nearly absent (0.2 mg) during the ensuing 6- to 9-hr period. The cumulative excretion of the glucuronide conjugate of canrenone amounted to 4.6 and 2.8 mg (2.3% and 1.4%) of the dose during these respective periods. A sustained retention of K was observed in 1 subject. Otherwise, as was anticipated in the absence of hyperaldosteronism, urinary electrolyte levels were essentially unchanged. Circulating aldosterone and plasma renin activity levels were essentially unaltered.