Drug interactions
Asenapine transdermal + Clozapine
Severity: Major
Asenapine transdermal and Clozapine: 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
Both clozapine and asenapine can prolong the QT interval. Giving them together adds to the risk of serious ventricular arrhythmias such as torsades de pointes. Asenapine also adds to the sedative and antipsychotic burden.
What this interaction means in plain words
Asenapine transdermal and Clozapine 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.
Why it happens
Additive pharmacodynamic effect on cardiac repolarisation through blockade of cardiac potassium channels.
What to do
Avoid combining two antipsychotics when an alternative exists. If it is unavoidable, get a baseline ECG, correct potassium and magnesium, and repeat the ECG after dose changes.
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
Frequently asked questions
Can I take Asenapine transdermal with Clozapine?
MediHelp rates the interaction as major. Asenapine transdermal and Clozapine 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 clozapine and asenapine can prolong the QT interval. Giving them together adds to the risk of serious ventricular arrhythmias such as torsades de pointes. Asenapine also adds to the sedative and antipsychotic burden.
How serious is the interaction between Asenapine transdermal and Clozapine?
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 combining two antipsychotics when an alternative exists. If it is unavoidable, get a baseline ECG, correct potassium and magnesium, and repeat the ECG after dose changes.
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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