PAPAVERINE IS AN ALKALOID PRESENT IN OPIUM AND NOT RELATED TO THE OTHER OPIUM ALKALOIDS. IT HAS A DIRECT RELAXANT EFFECT ON SMOOTH MUSCLE WHICH IS ATTRIBUTED IN PART TO ITS ABILITY TO INHIBIT PHOSPHODIESTERASE. IT IS USED FOR CEREBRAL, PERIPHERAL, AND CORONARY VASCULAR DISORDERS AND ALSO HAS AS AN ANTISPASMODIC FOR G.I. DISORDERS AND COUGH.