Pharmacodynamics of acidic triamterene derivatives and their esters and amides.

The diuretic, natriuretic and antikaliuretic effects of two acidic triamterene derivatives, carboxymethoxytriamterene (C2) and carboxybutoxytriamterene (C5), as well as some of their esters and amides were studied in male Wistar rats. The acids and their esters possess similar natriuretic and potassium retaining properties. The esters are nearly completely hydrolyzed to the corresponding acids; therefore, the acids themselves represent the active principle. Compared to the acids and esters the amides have a stronger effect on natriuresis and antikaliuresis. As the amides are excreted partially unhydrolyzed in urine, their pronounced natriuretic and potassium retaining effect must be due to the intact molecule.