[Comparison of the cardiac effects of triamterene and its phase II metabolite p-hydroxytriamterene sulphuric acid ester (author's transl].

The positive inotropic action of triamterene (TA) on isolated, electrically stimulated left atria was compared with that of its phase II metabolite, p-hydroxytriamterene sulphuric acid ester (OH-TA-ester). It was found that the metabolite also possesses a positive inotropic action, its potency, however, is about 10 times lower than that of triamterene.