Direct acting vasodilator, MOA is not known Reduces both right and left ventricular afterload by reducing pulmonary and systemic vascular resistance Results in increased cardiac output and decreased ventricular wall stress during systole Reduces renal vascular resistance and increases renal blood flow more than any other vasodilator except ACE inhibitors Preferred drug in CHF (ACE intolerant) with renal impairment is more often used in combination with isosorbide dinitrate