Drug interactions
Tolvaptan + Tucatinib
Severity: Major
Tolvaptan and Tucatinib: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Tucatinib is a strong CYP3A inhibitor and may substantially increase tolvaptan exposure. This raises the risk of excessive aquaresis, dehydration and overly rapid correction of sodium.
What this interaction means in plain words
Tolvaptan and Tucatinib can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Tolvaptan belongs to Endocrine; Tucatinib belongs to Oncology.
Why it happens
Inhibition of CYP3A4 decreases tolvaptan clearance.
What to do
Avoid the combination if possible. If unavoidable, reduce the tolvaptan dose per labeling and monitor serum sodium and fluid status closely.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Tolvaptan
- Atazanavir + Tolvaptan Contraindicated
- Ceritinib + Tolvaptan Contraindicated
- Cobicistat + Tolvaptan Contraindicated
- Conivaptan + Tolvaptan Contraindicated
- Darunavir + Tolvaptan Contraindicated
- Idelalisib + Tolvaptan Contraindicated
Other interactions of Tucatinib
- Cisapride + Tucatinib Contraindicated
- Eletriptan + Tucatinib Contraindicated
- Ergotamine + Tucatinib Contraindicated
- Flibanserin + Tucatinib Contraindicated
- Ranolazine + Tucatinib Contraindicated
- Amobarbital + Tucatinib Major
Frequently asked questions
Can I take Tolvaptan with Tucatinib?
MediHelp rates the interaction as major. Tolvaptan and Tucatinib can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Tucatinib is a strong CYP3A inhibitor and may substantially increase tolvaptan exposure. This raises the risk of excessive aquaresis, dehydration and overly rapid correction of sodium.
How serious is the interaction between Tolvaptan and Tucatinib?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible. If unavoidable, reduce the tolvaptan dose per labeling and monitor serum sodium and fluid status closely.
What other medicines interact with Tolvaptan?
MediHelp also lists interactions of Tolvaptan with, for example, Atazanavir, Ceritinib, Cobicistat. The full list is on the Tolvaptan page.
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