Drug interactions
Flecainide + Quinacrine
Severity: Moderate
Flecainide and Quinacrine: moderate 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
Quinacrine has been reported to inhibit CYP2D6, the main enzyme clearing flecainide, so flecainide exposure may rise. Because flecainide has a narrow therapeutic window, higher levels may cause conduction slowing, QRS widening and proarrhythmia.
What this interaction means in plain words
Flecainide and Quinacrine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Quinacrine inhibits CYP2D6-mediated metabolism of flecainide, reducing its clearance.
What to do
Monitor ECG (PR, QRS intervals) and flecainide plasma concentration when starting quinacrine. Reduce the flecainide dose if conduction intervals lengthen or toxicity signs appear.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Flecainide
- Flecainide + Nirmatrelvir Contraindicated
- Flecainide + Nirmatrelvir / ritonavir Contraindicated
- Flecainide + Pimozide Contraindicated
- Flecainide + Ritonavir Contraindicated
- Flecainide + Thioridazine Contraindicated
- Flecainide + Tipranavir Contraindicated
Frequently asked questions
Can I take Flecainide with Quinacrine?
MediHelp rates the interaction as moderate. Flecainide and Quinacrine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Quinacrine has been reported to inhibit CYP2D6, the main enzyme clearing flecainide, so flecainide exposure may rise. Because flecainide has a narrow therapeutic window, higher levels may cause conduction slowing, QRS widening and proarrhythmia.
How serious is the interaction between Flecainide and Quinacrine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor ECG (PR, QRS intervals) and flecainide plasma concentration when starting quinacrine. Reduce the flecainide dose if conduction intervals lengthen or toxicity signs appear.
What other medicines interact with Flecainide?
MediHelp also lists interactions of Flecainide with, for example, Nirmatrelvir, Nirmatrelvir / ritonavir, Pimozide. The full list is on the Flecainide page.
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