Drug interactions
Cobicistat + Quinidine
Severity: Major
Cobicistat and Quinidine: 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
Cobicistat inhibits CYP3A4, CYP2D6 and P-gp, raising quinidine concentrations. Quinidine has a narrow therapeutic index, and increased exposure raises the risk of QT prolongation and torsades de pointes.
What this interaction means in plain words
Cobicistat 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.
Cobicistat belongs to Miscellaneous; Quinidine belongs to Anti Parasitic.
Why it happens
Cobicistat inhibits CYP3A4 and P-gp, reducing quinidine metabolism and efflux.
What to do
Avoid if possible; otherwise reduce the quinidine dose and monitor ECG QTc and quinidine concentrations.
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 Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Other interactions of Cobicistat
- Alfuzosin + Cobicistat Contraindicated
- Apalutamide + Cobicistat Contraindicated
- Cobicistat + Colchicine Contraindicated
- Cobicistat + Dronedarone Contraindicated
- Cobicistat + Eletriptan Contraindicated
- Cobicistat + Eplerenone Contraindicated
Frequently asked questions
Can I take Cobicistat with Quinidine?
MediHelp rates the interaction as major. Cobicistat 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. Cobicistat inhibits CYP3A4, CYP2D6 and P-gp, raising quinidine concentrations. Quinidine has a narrow therapeutic index, and increased exposure raises the risk of QT prolongation and torsades de pointes.
How serious is the interaction between Cobicistat 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 if possible; otherwise reduce the quinidine dose and monitor ECG QTc and quinidine concentrations.
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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