An impurity of Felypressin. Felypressin is a Vasopressin 1 agonist, and will thus have effects at all Arginine vasopressin receptor 1As. It physiologically effects on vascular SMC’s due to the form in which it is administered. Its receptors are found in various sites around the body. The major points include the CNS, Liver, Anterior Pituitary, Muscle (both vascular and non-vascular smooth muscle), and Platelets (CLAMP).