Drug interactions
Posaconazole + Valbenazine
Severity: Major
Posaconazole and Valbenazine: 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
Posaconazole raises valbenazine active metabolite exposure through CYP3A4 inhibition, and both can prolong the QT interval. This increases risks of somnolence and ventricular arrhythmia.
What this interaction means in plain words
Posaconazole and Valbenazine 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.
Posaconazole belongs to Anti Fungals; Valbenazine belongs to Central Nervous System.
Why it happens
Strong CYP3A4 inhibition reduces valbenazine clearance, with additive QT prolongation.
What to do
Reduce the valbenazine dose to 40 mg once daily during co-administration. Monitor the ECG and electrolytes, especially in patients with QT risk factors.
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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole Contraindicated
Other interactions of Valbenazine
- Deutetrabenazine + Valbenazine Contraindicated
- Tranylcypromine + Valbenazine Contraindicated
- Amiodarone + Valbenazine Major
- Amisulpride + Valbenazine Major
- Apalutamide + Valbenazine Major
- Carbamazepine + Valbenazine Major
Frequently asked questions
Can I take Posaconazole with Valbenazine?
MediHelp rates the interaction as major. Posaconazole and Valbenazine 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. Posaconazole raises valbenazine active metabolite exposure through CYP3A4 inhibition, and both can prolong the QT interval. This increases risks of somnolence and ventricular arrhythmia.
How serious is the interaction between Posaconazole and Valbenazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Reduce the valbenazine dose to 40 mg once daily during co-administration. Monitor the ECG and electrolytes, especially in patients with QT risk factors.
What other medicines interact with Posaconazole?
MediHelp also lists interactions of Posaconazole with, for example, Artemether, Avanafil, Cobimetinib. The full list is on the Posaconazole page.
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