MICROZIDEŽ (hydrochlorothiazide, USP 12.5 mg) is the 3,4-dihydro derivative of chlorothiazide. Its chemical name is 6-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide. Its empirical formula is C7H8CIN304S2; its molecular weight is 297.74; and its structural formula is: