Drug interactions
Lenacapavir + Tolvaptan
Severity: Major
Lenacapavir and Tolvaptan: 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
Lenacapavir is a moderate CYP3A inhibitor, and tolvaptan is a sensitive CYP3A4 substrate. Exposure to tolvaptan may rise, causing excessive aquaresis and rapid sodium correction, and the effect may persist for months after the last subcutaneous dose.
What this interaction means in plain words
Lenacapavir and Tolvaptan 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.
Lenacapavir belongs to Anti Virals; Tolvaptan belongs to Endocrine.
Why it happens
Lenacapavir inhibits CYP3A4, reducing tolvaptan metabolism and increasing its exposure.
What to do
Avoid combination where possible or reduce tolvaptan dose with close monitoring of serum sodium and volume status. Continue monitoring for months after the last lenacapavir injection.
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 Lenacapavir
- Apalutamide + Lenacapavir Contraindicated
- Carbamazepine + Lenacapavir Contraindicated
- Enzalutamide + Lenacapavir Contraindicated
- Flibanserin + Lenacapavir Contraindicated
- Lenacapavir + Phenytoin Contraindicated
- Lenacapavir + Rifampicin Contraindicated
Frequently asked questions
Can I take Lenacapavir with Tolvaptan?
MediHelp rates the interaction as major. Lenacapavir and Tolvaptan 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. Lenacapavir is a moderate CYP3A inhibitor, and tolvaptan is a sensitive CYP3A4 substrate. Exposure to tolvaptan may rise, causing excessive aquaresis and rapid sodium correction, and the effect may persist for months after the last subcutaneous dose.
How serious is the interaction between Lenacapavir and Tolvaptan?
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 combination where possible or reduce tolvaptan dose with close monitoring of serum sodium and volume status. Continue monitoring for months after the last lenacapavir injection.
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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