Hydrochlorothiazide - 15 N 2 , 13 C,d 2 is 15 N and deuterated labeled Hydrochlorothiazide. Hydrochlorothiazide (HCTZ), an orally active diuretic agent of the thiazide class, inhibits transforming TGF-β/Smad signaling pathway. Hydrochlorothiazide has direct vascular relaxant effects via opening of the calcium-activated potassium (KCA) channel. Hydrochlorothiazide improves cardiac function, reduces fibrosis and has antihypertensive effect.