Tolvaptan
SAMSCA
What it isSelective V2 vasopressin antagonist; hyponatremia and autosomal dominant polycystic kidney disease.
Why this oneIt clears free water without sodium loss and slows kidney enlargement in polycystic disease.
What limits it⚑ Overrapid sodium correction can cause osmotic demyelination, requiring inpatient initiation; liver toxicity drives REMS monitoring in ADPKD.
FDA-approved for
- hyponatremia (2009)
- ADPKD (2018)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Hyponatremia (hypervolemic/euvolemic; HF, cirrhosis, SIADH) | Adult | 15 mg QD | 30 mg QD | 60 mg QD |
Titration >=24 hours between dose increases
Renal No adjustment needed (no data if CrCl <10)
Hepatic Avoid in underlying liver disease (exposure not clinically affected)
Limit to <=30 days; increase dose no sooner than every 24 h
Instructions
- Initiate/re-initiate in a hospital; monitor serum sodium.
- Do not treat for more than 30 days (liver injury risk).
- Avoid fluid restriction during first 24 h; patient may drink to thirst.
- Do not use with strong CYP3A inhibitors.
Contraindications
- ADPKD outside of FDA-approved REMS
- Unable to sense or respond to thirst
- Hypovolemic hyponatremia
- Concomitant strong CYP3A inhibitors
- Anuria
Cautions
- Too-rapid sodium correction causes osmotic demyelination
- Liver injury - limit to 30 days, avoid in liver disease
- Dehydration/hypovolemia
- Avoid with hypertonic saline
- Hyperkalemia
- Urinary outflow obstruction
Adverse reactions
- Thirst
- Dry mouth
- Asthenia
- Constipation
- Pollakiuria/polyuria
- Hyperglycemia
Pregnancy Insufficient human data; animal embryo-fetal toxicity
Lactation Breastfeeding not recommended
⚠ BOXED WARNINGS
- Initiate in hospital; too-rapid sodium correction causes osmotic demyelination
- Hepatotoxicity in the ADPKD indication
Cost, est. cash$10–$500/month
Generic entry2026
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
Mechanism of action: Tolvaptan ballicule
