# Vasopressin > The body’s water-conservation hormone — a 9-amino-acid posterior-pituitary peptide, near-twin of oxytocin, used as a vasopressor and (as desmopressin) for diabetes insipidus. - Also known as: Arginine vasopressin, AVP, Antidiuretic hormone, ADH, Vasostrict, Desmopressin (analog) - Class: Peptide Hormones - FDA approved: Yes - Canonical page: https://americanpeptide.com/catalog/vasopressin ## Overview Vasopressin is a cyclic nonapeptide released from the posterior pituitary that controls how much water the kidney retains and constricts blood vessels. It differs from oxytocin by only two residues, yet does an entirely different job — a textbook example of how a tiny sequence change repurposes a hormone. In the clinic the native hormone (Vasostrict) is a vasopressor for refractory shock, while its engineered analog desmopressin (dDAVP) treats central diabetes insipidus, bedwetting, and some bleeding disorders. Vasopressin and oxytocin are the two posterior-pituitary nonapeptides, structurally almost identical — they differ at only two of nine positions and share the same disulfide-closed ring — but functionally distinct. That near-identity is a classic illustration of how peptide hormones diversify: gene duplication of an ancestral nonapeptide, then a few substitutions that switch receptor preference and physiological role. Its central job is water balance. When the body is dehydrated, vasopressin tells the kidney to reabsorb water, concentrating the urine; failure of this signal — from the pituitary (central) or the kidney (nephrogenic) — causes diabetes insipidus, with copious dilute urine and thirst. The V2-selective analog desmopressin restores that signal in central diabetes insipidus and is also used for nocturnal enuresis and to raise clotting factors in mild hemophilia and von Willebrand disease. The native hormone’s second face is vascular. Through V1a receptors it constricts blood vessels, which is why a vasopressin infusion (Vasostrict) is used to raise blood pressure in septic and other vasodilatory shock when catecholamines alone are not enough. One molecule, two receptor systems, two very different clinical uses — selected apart by which analog you reach for. ## Mechanism Agonist at the V2 receptor in the renal collecting duct (inserting aquaporin-2 water channels to concentrate urine) and the V1a receptor on vascular smooth muscle (vasoconstriction). Desmopressin is V2-selective, giving the antidiuretic effect without the pressor action. ## Chemistry | Property | Value | | --- | --- | | Molecular weight | 1084.2 Da | | CAS number | 113-79-1 | ## Sequence ``` CYFQNCPRG (1–6 disulfide, C-terminal amide) ``` ## Research areas Studied in: Diabetes insipidus, Vasodilatory shock, Osmoregulation, Peptide hormones. Guides on this site: - [Peptide Hormone Synthesis](https://americanpeptide.com/research-areas/peptide-hormones): How hormone sequences are turned into pure, stable, manufacturable synthetic drugs. ## Key research - Diabetes insipidus — desmopressin (V2-selective) replaces the antidiuretic signal in central DI; the disorder is the classic demonstration of the hormone’s role. - Vasodilatory shock — native vasopressin is a second-line vasopressor (V1a-mediated) for septic and post-cardiotomy shock refractory to catecholamines. - Hemostasis — desmopressin releases von Willebrand factor and factor VIII, used in mild hemophilia A and von Willebrand disease. - Structure–function — two-residue difference from oxytocin reroutes receptor selectivity, a canonical peptide-hormone case study. - Osmoregulation — the V2/aquaporin-2 axis is the molecular basis of renal water reabsorption. ## Storage, handling & synthesis **Synthesis.** A nonapeptide built by solid-phase synthesis and then oxidatively folded to close its single 1–6 disulfide, with a C-terminal amide. The synthetically interesting object is the analog: desmopressin (dDAVP) re-engineers the hormone with a deaminated position 1 and a D-arginine at position 8 — a stereochemical substitution that resists aminopeptidase cleavage, strips out the V1a pressor activity, and extends the half-life. It is a compact lesson in how D-amino acids and end-group edits convert a labile hormone into a dosable drug. Identity and disulfide connectivity are the key release tests. ## FAQs ### What does vasopressin do? It conserves body water by making the kidney reabsorb it (its "antidiuretic" action) and it constricts blood vessels. As a drug, native vasopressin is used as a vasopressor in shock, and its analog desmopressin treats central diabetes insipidus. ### How is it related to oxytocin? They are near-twins — both 9-amino-acid posterior-pituitary hormones that differ at only two positions — yet vasopressin governs water balance and blood pressure while oxytocin governs labor and bonding. ### What is desmopressin? Desmopressin (dDAVP) is a synthetic vasopressin analog engineered to act selectively at the V2 receptor, giving the water-retaining effect without raising blood pressure. It is used for central diabetes insipidus, bedwetting, and some bleeding disorders. ### Is this medical advice? No — this is a research and educational reference, not dosing guidance. Vasopressin and its analogs are prescription medicines. ## Latest research Recent trials and publications mentioning Vasopressin, pulled automatically from ClinicalTrials.gov and PubMed (unfiltered search results, refreshed daily). ### Recent trials - [Levothyroxine Supplementation for Heart Transplant Recipients](https://clinicaltrials.gov/study/NCT06428097) — RECRUITING · PHASE1 · NCT06428097 - [Plasma Oxytocin Response to Oral Estrogens in Healthy Controls and AVP-Deficiency](https://clinicaltrials.gov/study/NCT07361263) — RECRUITING · NA · NCT07361263 - [Desmopressin Stimulation Test Performance in ACTH-Dependent Cushing Syndrome](https://clinicaltrials.gov/study/NCT06635629) — RECRUITING · PHASE2 · NCT06635629 - [CAlcium and VAsopressin Following Injury Early Resuscitation (CAVALIER) Trial](https://clinicaltrials.gov/study/NCT05958342) — RECRUITING · PHASE2 · NCT05958342 - [Copeptin and Acute Coronary Syndrome Without ST-segment Elevation](https://clinicaltrials.gov/study/NCT01334645) — COMPLETED · NA · NCT01334645 - [ATLCAR.CD30.CCR4 for CD30+ HL ATLCAR.CD30.CCR4 Cells](https://clinicaltrials.gov/study/NCT06090864) — RECRUITING · PHASE1, PHASE2 · NCT06090864 --- Source: AmericanPeptide.com — https://americanpeptide.com/catalog/vasopressin Data license: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Attribution: AmericanPeptide.com. Research reference only — computational and educational content, not medical advice.