Felypressin is a non-catecholamine

Catecholamine

Catecholamines are molecules that have a catechol nucleus consisting of benzene with two hydroxyl side groups and a side-chain amine. They include dopamine, as well as the "fight-or-flight" hormones adrenaline and noradrenaline released by the adrenal medulla of the adrenal glands in response to...

 vasoconstrictor that is chemically related to vasopressin

Vasopressin

Arginine vasopressin , also known as vasopressin, argipressin or antidiuretic hormone , is a neurohypophysial hormone found in most mammals, including humans. Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue's...

, the posterior pituitary hormone

Hormone

A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...

. It is added to some local anaesthetics such as prilocaine

Prilocaine

Prilocaine is a local anesthetic of the amino amide type first prepared by Claes Tegner and Nils Lofgren. In its injectable form , it is often used in dentistry. It is also often combined with lidocaine as a preparation for dermal anesthesia , for treatment of conditions like paresthesia...

 in a concentration of 0.03 IU/ml. Felypressin is a Vasopressin 1 agonist, and will thus have affects at all Arginine vasopressin receptor 1A

Arginine vasopressin receptor 1A

Arginine vasopressin receptor 1A is one of the three major receptor types for arginine vasopressin , and is present throughout the brain, as well as in the periphery in the liver, kidney, and vasculature.Arginine vasopressin receptor 1A is also known as:* V1a vasopressin receptor* antidiuretic...

s. It will, however, have its main physiological effects on vascular SMC's due to the form in which it is administered.

V1 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).

Another example of a V1 agonist is terlipressin

Terlipressin

Terlipressin is an analogue of vasopressin used as a vasoactive drug in the management of hypotension. It has been found to be effective when norepinephrine does not help.Indications for use include norepinephrine-resistant septic shock and hepatorenal syndrome...

 - which is used in oesophageal varices.