Notes: Triamterene-d5 is intended for use as an internal standard for the quantification of triamterene (Item No. 21242) by GC- or LC-MS. Triamterene is an inhibitor of the epithelial sodium channel (ENaC; IC50 = 4.5 µM for the rat channel).{33172} In vivo, triamterene (0.5-32 mg/animal) enhances sodium secretion and decreases potassium secretion in adrenalectomized rats.{57562} Formulations containing triamterene have been used in the treatment of edema.