Conivaptan
vaptans
Vasopressin receptor antagonists (vaptans)
An intravenous vasopressin V1a/V2 receptor blocker that makes the kidney excrete free water, raising sodium in hospitalised patients with hyponatraemia.
Quick facts
- Group
- Vasopressin receptor antagonists (vaptans)
- Target
- Vasopressin V2 receptor (and V1a)
- Key effects
- Infusion-site reactions and phlebitis · Headache
- Monitor
- Serum sodium often · Potassium · Infusion site
- ATC
- C03XA02
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows conivaptan bound to the human vasopressin V2 receptor (with a helper antibody fragment used to solve the structure).
Conivaptan is a non-peptide antagonist of both vasopressin V1a and V2 receptors, with higher affinity for V2. Blocking V2 receptors in the collecting duct stops vasopressin from inserting aquaporin-2 water channels, so the kidney excretes free water without losing much sodium or potassium (aquaresis), and serum sodium rises. V1a block may cause some vasodilation, one reason it is avoided in cirrhosis.
- Blocks V2 (and V1a) vasopressin receptors
- Collecting duct inserts fewer aquaporin-2 channels
- Free water is excreted (aquaresis)
- Serum sodium rises
Indications
- Euvolaemic or hypervolaemic hyponatraemia in hospitalised patients (for example SIADH) Hyponatraemia →
- Hyponatraemia from inappropriate antidiuretic hormone secretion Syndrome of inappropriate antidiuretic hormone secretion (SIADH) →
Adverse effects
Common
- Infusion-site reactions and phlebitis
- Headache, thirst, fever
- Nausea, constipation
- Low potassium
Contraindications
- Hypovolaemic hyponatraemia
- Strong CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin, ritonavir, indinavir)
- Avoided in cirrhosis, where V1a block may worsen variceal bleeding
Key interactions
- Strong CYP3A4 inhibitors
- Large rise in conivaptan levels; contraindicated.
- CYP3A4 substrates (midazolam, simvastatin, amlodipine) and digoxin
- Their levels rise; used with caution.
- Loop and thiazide diuretics
- More hypotension and volume loss.
What is monitored
- Serum sodium often, to keep the rise within safe limits
- Potassium, blood pressure and volume status
- Infusion site
- Neurological status (signs of osmotic demyelination)
Administration and safety
- Intravenous infusion through a large vein; the site is changed regularly to limit phlebitis.
- For short-term in-hospital use only.
- Usually not combined with conventional diuretics or with fluid loading.
Pregnancy and breastfeeding
Data in pregnancy are limited; it is used only if the benefit justifies the risk.
Nursing care
- Before: confirm that the patient is not hypovolaemic; record sodium, potassium and blood pressure.
- During: check sodium as often as ordered; report a fast rise or new neurological signs at once.
- Inspect the infusion site for redness, pain or swelling.
- Record intake, output and thirst.
Pharmacokinetics
- Absorption
- Intravenous only, for short-term use in hospital.
- Distribution
- Highly protein-bound.
- Metabolism
- Liver, by CYP3A4; it is also a potent CYP3A4 inhibitor.
Test yourself
Think of the answer, then tap the question to see it.
Which receptors does conivaptan block?
Vasopressin V1a and V2 receptors (higher affinity for V2).
What is the most important danger when correcting sodium with conivaptan?
Too-rapid correction, which can cause osmotic demyelination.
Why is conivaptan restricted with ketoconazole or ritonavir?
It is metabolised by CYP3A4, so strong inhibitors raise its levels sharply.
Connections
← Back to the class: Vasopressin receptor antagonists (vaptans)
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Conivaptan: a step forward in the treatment of hyponatremia? (Therapeutics and Clinical Risk Management, via PubMed Central, 2008); Cryo-EM structure of conivaptan-bound human vasopressin V2 receptor complex with Fab (RCSB Protein Data Bank, 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.