Drug interactions
Quetiapine + Quinidine
Severity: Major
Quetiapine and Quinidine: 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 combining them raises the risk of torsades de pointes. Risk is greater with electrolyte disturbance, bradycardia, structural heart disease or overdose. Quinidine may also modestly raise quetiapine exposure through CYP3A4 inhibition.
What this interaction means in plain words
Quetiapine and Quinidine 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.
Quetiapine belongs to Central Nervous System; Quinidine belongs to Anti Parasitic.
Why it happens
Additive QT prolongation, with a possible minor CYP3A4-mediated rise in quetiapine levels.
What to do
Avoid the combination where possible, or obtain a baseline and follow-up ECG and correct potassium and magnesium. Choose a non-QT-prolonging alternative in high-risk patients.
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 Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine 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 Quetiapine with Quinidine?
MediHelp rates the interaction as major. Quetiapine and Quinidine 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 combining them raises the risk of torsades de pointes. Risk is greater with electrolyte disturbance, bradycardia, structural heart disease or overdose. Quinidine may also modestly raise quetiapine exposure through CYP3A4 inhibition.
How serious is the interaction between Quetiapine and Quinidine?
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, or obtain a baseline and follow-up ECG and correct potassium and magnesium. Choose a non-QT-prolonging alternative in high-risk patients.
What other medicines interact with Quinidine?
MediHelp also lists interactions of Quinidine with, for example, Adagrasib, Arsenic trioxide, Artemether / lumefantrine. The full list is on the Quinidine page.
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