Drug interactions
Pimavanserin + Tetrabenazine
Severity: Major
Pimavanserin and Tetrabenazine: major interaction.
Last updated Sources: US FDA label
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
Tetrabenazine causes dose-related QTc prolongation, and pimavanserin also prolongs the QT interval, increasing the risk of torsades de pointes. Tetrabenazine is also metabolized by CYP2D6, but pimavanserin does not significantly affect that enzyme.
What this interaction means in plain words
Pimavanserin and Tetrabenazine 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.
Pimavanserin belongs to Central Nervous System; Tetrabenazine belongs to Central Nervous System.
Why it happens
Additive QTc prolongation.
What to do
Avoid the combination if possible; if both are needed, obtain a baseline ECG and monitor QTc and electrolytes, particularly with tetrabenazine dose increases.
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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References
Other interactions of Pimavanserin
- Lefamulin + Pimavanserin Contraindicated
- Pimavanserin + Pimozide Contraindicated
- Pimavanserin + Vandetanib Contraindicated
- Adagrasib + Pimavanserin Major
- Amiodarone + Pimavanserin Major
- Amisulpride + Pimavanserin Major
Other interactions of Tetrabenazine
- Dronedarone + Tetrabenazine Contraindicated
- Isocarboxazid + Tetrabenazine Contraindicated
- Linezolid + Tetrabenazine Contraindicated
- Phenelzine + Tetrabenazine Contraindicated
- Pimozide + Tetrabenazine Contraindicated
- Procarbazine + Tetrabenazine Contraindicated
Frequently asked questions
Can I take Pimavanserin with Tetrabenazine?
MediHelp rates the interaction as major. Pimavanserin and Tetrabenazine 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. Tetrabenazine causes dose-related QTc prolongation, and pimavanserin also prolongs the QT interval, increasing the risk of torsades de pointes. Tetrabenazine is also metabolized by CYP2D6, but pimavanserin does not significantly affect that enzyme.
How serious is the interaction between Pimavanserin and Tetrabenazine?
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 both are needed, obtain a baseline ECG and monitor QTc and electrolytes, particularly with tetrabenazine dose increases.
What other medicines interact with Pimavanserin?
MediHelp also lists interactions of Pimavanserin with, for example, Lefamulin, Pimozide, Vandetanib. The full list is on the Pimavanserin page.
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