<unk> (oral) is a vasodilator that is FDA approved for the treatment of hypertension that is symptomatic or associated with target organ damage and is not manageable with maximum therapeutic doses of diuretic plus two other antihypertensive drugs. There is a Black Box Warning for this drug as shown here.  Common adverse reactions include hypotension, hirsutism, hypertrichosis, fluid retention, and hypernatremia.
Minoxidil 
Endralazine
Alprostadil 
Nitroprusside
Isosorbide dinitrate
Balsalazide
Nadolol 
Captopril