Apresoline, hydralazine hydrochloride USP, is an antihypertensive, available as 10-, 25-, 50-, and 100-mg tablets for oral administration. Hydralazine hydrochloride, USP is a white to off-white, odorless crystalline powder. It is soluble in water, slightly soluble in alcohol, and very slightly soluble in ether. It melts at about 275°C, with decomposition, and has a molecular weight of 196.84. Inactive Ingredients.