Terlipressin, an analogue of vasopressin, acts on three different receptors, vasopressin receptor V1a (which initiates vasoconstriction, liver gluconeogenesis, platelet aggregation and release of factor VIII), vasopressin receptor V1b (which mediates corticotrophin secretion from the pituitary) and vasopressin receptor V2 which controls free water reabsorption in the renal medullar. The binding of terlipressin to the V2 receptor activates adenylate cyclase which causes the release of aquaporin 2 channels into the cells lining the renal medullar duct. This allows water to be reabsorbed down an osmotic gradient so the urine is more concentrated.
Terlipressin is a medicine similar to a naturally occurring hormone present in the body, known as antidiuretic hormone (ADH) or vasopressin. ADH has two main effects in the body. Firstly, it causes narrowing of blood vessels (vasoconstriction), thereby limiting blood flow to a particular area of the body. It also acts on receptors in the kidney to retain water in the body, which helps to prevent excessive loss of water in the urine.