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# Vasopressin

The natural antidiuretic hormone given by IV infusion. In shock that persists despite fluids and noradrenaline it raises blood pressure.

Updated 2026-11-01

- Class: [Vasopressin and its analogues](https://durgical.com/en/pharmacology/classes/vasopressin-and-its-analogues/)
- Receptor: Vasopressin V1a receptor (and V2 in the kidney)
- ATC code: H01BA01

## ⚠ High-alert medication

An error with this medicine can cause serious harm: double checks and protocols are used.

Also called: Argipressin, Antidiuretic hormone (ADH)

## Mechanism of action

Vasopressin binds V1 receptors on vascular smooth muscle, coupled to Gq and phospholipase C; intracellular calcium rises and vessels constrict, especially in the skin, gut and muscle. Through renal V2 receptors, coupled to adenylyl cyclase, it also causes antidiuresis. In vasodilatory shock, where the body's own vasopressin is relatively low, a small infusion restores vascular tone and lets catecholamine doses fall.

- Vasopressin binds V1 receptors on vascular smooth muscle
- Gq and phospholipase C raise intracellular calcium
- Vessels constrict and blood pressure rises
- On renal V2 receptors it also reduces urine output

## Pharmacokinetics

**Absorption**
Given by continuous IV infusion; not effective by mouth

**Metabolism**
Cleaved quickly by proteases and peptidases

**Half-life**
Very short, so the effect stops soon after the infusion is stopped

## Indications

- Vasodilatory shock (such as septic shock) that remains hypotensive despite fluids and catecholamines [Sepsis and septic shock →](https://durgical.com/en/conditions/sepsis-and-septic-shock/)

## Adverse effects

### Common

- Bradycardia
- Reduced cardiac output
- Hyponatraemia
- Skin and finger ischaemia

### Serious (rare, important)

- Mesenteric, digital and myocardial ischaemia
- Tachyarrhythmias and atrial fibrillation
- Right heart failure

## Contraindications

- Known allergy to vasopressin or to chlorobutanol (a preservative in some vials)

## Key interactions

**Catecholamines (noradrenaline, adrenaline)**
Additive pressor effect

**Indomethacin**
May prolong the effect of vasopressin

**Ganglionic blockers and drugs that cause SIADH**
Greater pressor response

**Drugs that cause diabetes insipidus (lithium, demeclocycline, foscarnet, clozapine)**
Weaker pressor response

## What is monitored

- Continuous blood pressure and heart rhythm
- Urine output
- Serum sodium
- Skin, fingers and abdomen for signs of ischaemia

## Administration and safety

- Diluted before use and given by continuous infusion with a pump, as the product label describes
- Added to catecholamines in refractory shock; it is not a replacement for fluids
- Look-alike risk with desmopressin: confirm the drug and the product

## Nursing care

- Monitor blood pressure continuously, ideally with an arterial line, and heart rhythm
- Check fingers, skin colour and the abdomen for ischaemia
- Track sodium and urine output
- Never stop the infusion abruptly without an order; blood pressure can fall quickly

## Pregnancy and breastfeeding

May cause tonic uterine contractions; in pregnancy it is used only when the mother's life requires it.

## Memory aid

V1 = Vessels (squeeze), V2 = Water (kidney): vasopressin works both, but in shock we want the V1 squeeze.

## Test yourself

Think of the answer, then tap the question to see it.

## In septic shock, when is vasopressin added?

When hypotension persists despite adequate fluids and catecholamines; it is added to noradrenaline, not used instead of fluids.

## Which receptor and second messenger explain vasopressin's vasoconstriction?

The V1 receptor coupled to Gq: phospholipase C and IP3 release intracellular calcium.

## What should the nurse look for at the fingers and abdomen during a vasopressin infusion?

Signs of ischaemia: pale or dusky fingers, and abdominal pain or distension suggesting mesenteric ischaemia.

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## Related drugs

- [Desmopressin](https://durgical.com/en/pharmacology/desmopressin/)

## Related conditions

- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)

[← Back to the class: Vasopressin and its analogues](https://durgical.com/en/pharmacology/classes/vasopressin-and-its-analogues/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - VASOPRESSIN injection, solution](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=cce1a220-3178-49ec-b046-f0cb134cf051) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=H01BA01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Farmacología básica y clínica (Katzung), 16.ª ed., cap. 37 (McGraw Hill, 2025).

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Representative model, for educational purposes only.

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