Vasopressin is the parent molecule of one of the oldest and most instructive families in peptide pharmacology. Three of its analogues are UK-licensed medicines — desmopressin, terlipressin and argipressin (synthetic vasopressin itself) — and each exists because medicinal chemists learned to steer a single nonapeptide towards one of three different receptors. This explainer compares the three, sets out what is licensed and for what, and frames the class under UK law.

One hormone, three receptors

Arginine vasopressin (AVP) is a nonapeptide — Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly-NH2 — cyclised by a disulfide bridge between its first and sixth cysteines. It was isolated and synthesised in 1953 by Vincent du Vigneaud's group, work recognised by the 1955 Nobel Prize in Chemistry [1]. The endogenous hormone is released from the posterior pituitary and regulates plasma osmolality by promoting water reabsorption in the renal collecting duct.

AVP signals through three G protein-coupled receptors [1]:

  • V1a — vascular smooth-muscle cells, where activation causes vasoconstriction and platelet aggregation;
  • V1b — the anterior pituitary, where it drives ACTH release;
  • V2 — renal collecting-duct principal cells, where it triggers aquaporin-2 insertion and antidiuresis.

Because AVP binds all three, its clinical use is limited by non-selectivity and by a very short half-life of roughly 6–20 minutes [1]. Each of the three licensed analogues is an answer to one or both of those problems.

Desmopressin: the V2-selective workhorse

Desmopressin — 1-deamino-8-D-arginine vasopressin (dDAVP) — substitutes D-arginine at position 8 and deaminates the N-terminus. Those changes give a molecule whose antidiuretic activity is enhanced by roughly an order of magnitude while the vasopressor effect falls by about 1500-fold relative to vasopressin, so clinically active antidiuretic doses sit far below the threshold for a pressor effect [3]. Its plasma half-life is longer than the parent hormone — on the order of 90–190 minutes in the review literature, with the SPC describing a slow elimination phase of 51–158 minutes [1][3].

In the UK desmopressin is a prescription-only medicine (POM). Its licensed indications include central (cranial) diabetes insipidus, primary nocturnal enuresis, and nocturia due to idiopathic nocturnal polyuria; at higher doses it is also used as a haemostatic agent in mild haemophilia A and type 1 von Willebrand disease, where it raises factor VIII and von Willebrand factor [1][6]. The main safety signal to state plainly is hyponatraemia, which can be severe where antidiuresis is prolonged — a particular concern in older patients and those with renal impairment [1].

Terlipressin: a prodrug tuned for V1

Terlipressin is the triglycyl derivative of lysine-vasopressin. It is essentially inactive as administered and is converted by endothelial peptidases into lysine-vasopressin, which makes it a long-acting, V1-predominant vasoconstrictor with a plasma half-life of roughly 240–360 minutes [1][2]. By constricting the splanchnic circulation it lowers portal pressure and improves renal perfusion — the basis of its two UK-licensed uses: bleeding oesophageal varices, and emergency hospital treatment of type 1 hepatorenal syndrome (HRS) [4].

That second indication carries a material safety update. Following the CONFIRM trial, the MHRA advised that in type 1 HRS terlipressin reverses the syndrome more often than placebo (32% versus 17%, p=0.0006) but is associated with a higher rate of serious or fatal respiratory failure — respiratory failure and dyspnoea are now rated very common — and with an increased risk of sepsis and septic shock [4][5]. UK prescriber advice is to avoid terlipressin in advanced renal dysfunction and in severe liver disease unless benefit is judged to outweigh risk, to monitor daily for infection and respiratory deterioration, and to consider continuous infusion rather than bolus [4]. This advice applies to the HRS indication; it does not apply to use for bleeding oesophageal varices [4].

Argipressin: the non-selective parent, used when vasoconstriction is the point

Argipressin — the synthetic form of human AVP — is used as a vasopressor in vasodilatory and septic shock, typically as an adjunct to catecholamines. It is the least selective of the three: it activates V1a to raise vascular tone but also V2, so hyponatraemia, reduced cardiac output and platelet effects are part of its known profile [1][2]. It is a POM and a hospital medicine.

The UK licensing picture

All three are prescription-only medicines under the Human Medicines Regulations 2012, which sit within the framework of the Medicines Act 1968. They are licensed products with MHRA Summaries of Product Characteristics and defined indications — the opposite of the grey-market "research peptide" category. Felypressin, a V1-selective analogue used as a dental local-anaesthetic vasoconstrictor, belongs to the same family but is not discussed in detail here [1].

How this class grades

On Peptide Data's four-tier scale these compounds carry a Strong grade, but only within their licensed, clinician-administered indications — the grading reflects the human randomised-trial and regulatory record, not any use outside those indications. A licensed medicine is not a research reagent: its indications, monitoring requirements and contraindications are written into the SPC, and nothing here should be read as guidance for use in humans outside a prescriber's care.

Research use only

Peptide Data covers this class as reference material for laboratory and educational research. Nothing in this article is consumption, dosing or self-administration advice, and none of it should be taken as a statement that any peptide treats, cures or prevents any condition. Handling and study of these compounds outside a licensed clinical setting is a matter for UK law, which reserves their supply and use to prescription.

This article is AI-researched and editorially reviewed. It is provided for research and educational purposes only and is not medical advice. Research peptides are not licensed for human consumption in the UK.