Evidence for an acute antimagnesiuretic effect of triamterene derivatives.

The acute natriuretic, antikaliuretic and antimagnesiuretic effects of two triamterene derivatives, carboxybutoxytriamterene ethyl amide and dimethylaminohydroxypropoxytriamterene (RPH 2823), are shown in male Wistar rats during urine collection periods of 1 to 2.5 h. In combination with furosemide both compounds reduce the potassium excretion that is caused by the loop diuretic. Furthermore, RPH 2823 strongly decreases the magnesiuresis after application of furosemide, and the ethyl amide derivative (25 µmol/kg) reduces the magnesium losses produced by 25 µmol/kg furosemide close to control values. The evaluation of dose-response curves gave further evidence for the hypothesis that the renal handling of K(-) and Mg(2-) is coupled to some extent.