Drug interactions
Clozapine + Vandetanib
Severity: Major
Clozapine and Vandetanib: major interaction.
Last updated Sources: UK SmPC
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
Vandetanib causes marked, dose-related QT prolongation and carries a boxed warning for torsades de pointes and sudden death. Adding clozapine, which also prolongs the QT interval, increases the arrhythmia risk further.
What this interaction means in plain words
Clozapine and Vandetanib 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.
Clozapine belongs to Central Nervous System; Vandetanib belongs to Oncology.
Why it happens
Additive pharmacodynamic QT prolongation through hERG potassium channel blockade.
What to do
Avoid the combination and select a non-QT-prolonging alternative for the psychiatric indication if possible. If it cannot be avoided, monitor ECGs and electrolytes frequently.
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
- Clozapine Viatris 100 mg Orodispersible Tablets - SmPC sections 4.3/4.5 (class statement: medicines known to increase QTc interval; "caution should be exercised when clozapine is prescribed with medicines known to increase QTc interval, or causing electrolyte imbalance.") — electronic medicines compendium (UK SmPC)
Other interactions of Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Other interactions of Vandetanib
- Amiodarone + Vandetanib Contraindicated
- Amisulpride + Vandetanib Contraindicated
- Amitriptyline + Vandetanib Contraindicated
- Anagrelide + Vandetanib Contraindicated
- Asenapine + Vandetanib Contraindicated
- Chloroquine + Vandetanib Contraindicated
Frequently asked questions
Can I take Clozapine with Vandetanib?
MediHelp rates the interaction as major. Clozapine and Vandetanib 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. Vandetanib causes marked, dose-related QT prolongation and carries a boxed warning for torsades de pointes and sudden death. Adding clozapine, which also prolongs the QT interval, increases the arrhythmia risk further.
How serious is the interaction between Clozapine and Vandetanib?
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 and select a non-QT-prolonging alternative for the psychiatric indication if possible. If it cannot be avoided, monitor ECGs and electrolytes frequently.
What other medicines interact with Clozapine?
MediHelp also lists interactions of Clozapine with, for example, Deferiprone, Irinotecan, Pimozide. The full list is on the Clozapine page.
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