Drug interactions
Posaconazole + Quetiapine
Severity: Major
Posaconazole and Quetiapine: 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
Posaconazole strongly inhibits CYP3A4, the main route of quetiapine clearance, so quetiapine exposure can rise markedly, causing sedation, orthostatic hypotension and QT prolongation. Both drugs can also lengthen the QT interval independently.
What this interaction means in plain words
Posaconazole and Quetiapine 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; Quetiapine belongs to Central Nervous System.
Why it happens
CYP3A4 inhibition raising quetiapine levels plus additive QT prolongation.
What to do
Reduce the quetiapine dose substantially (labeling advises about one sixth of the usual dose with strong CYP3A4 inhibitors) and monitor ECG, electrolytes and sedation. Increase the dose again after posaconazole is stopped.
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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole Contraindicated
Other interactions of Quetiapine
- Adagrasib + Quetiapine Major
- Amiodarone + Quetiapine Major
- Amisulpride + Quetiapine Major
- Amoxapine + Quetiapine Major
- Anagrelide + Quetiapine Major
- Apalutamide + Quetiapine Major
Frequently asked questions
Can I take Posaconazole with Quetiapine?
MediHelp rates the interaction as major. Posaconazole and Quetiapine 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 strongly inhibits CYP3A4, the main route of quetiapine clearance, so quetiapine exposure can rise markedly, causing sedation, orthostatic hypotension and QT prolongation. Both drugs can also lengthen the QT interval independently.
How serious is the interaction between Posaconazole and Quetiapine?
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 quetiapine dose substantially (labeling advises about one sixth of the usual dose with strong CYP3A4 inhibitors) and monitor ECG, electrolytes and sedation. Increase the dose again after posaconazole is stopped.
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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