Drug interactions
Perphenazine + Tetrabenazine
Severity: Major
Perphenazine and Tetrabenazine: 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
Both drugs can prolong the QT interval, so their combination raises the risk of torsades de pointes and other serious ventricular arrhythmias. Both also cause sedation and extrapyramidal effects, which may add to the burden.
What this interaction means in plain words
Perphenazine 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.
Perphenazine belongs to Central Nervous System; Tetrabenazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation through cardiac repolarization effects; perphenazine also inhibits CYP2D6, which raises tetrabenazine active metabolite exposure.
What to do
Avoid the combination where possible. If it is used, obtain a baseline ECG, correct potassium and magnesium, and monitor QTc, keeping tetrabenazine doses low.
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 Perphenazine
- Ibutilide + Perphenazine Contraindicated
- Perphenazine + Pimozide Contraindicated
- Perphenazine + Thioridazine Contraindicated
- Adagrasib + Perphenazine Major
- Alfentanil + Perphenazine Major
- Amiodarone + Perphenazine 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 Perphenazine with Tetrabenazine?
MediHelp rates the interaction as major. Perphenazine 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. Both drugs can prolong the QT interval, so their combination raises the risk of torsades de pointes and other serious ventricular arrhythmias. Both also cause sedation and extrapyramidal effects, which may add to the burden.
How serious is the interaction between Perphenazine 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 where possible. If it is used, obtain a baseline ECG, correct potassium and magnesium, and monitor QTc, keeping tetrabenazine doses low.
What other medicines interact with Perphenazine?
MediHelp also lists interactions of Perphenazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Perphenazine page.
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