Drug interactions
Cobicistat + Flecainide
Severity: Major
Cobicistat and Flecainide: 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 CYP2D6 as well as CYP3A4 and can increase flecainide concentrations. This raises the risk of conduction abnormalities and ventricular arrhythmias.
What this interaction means in plain words
Cobicistat and Flecainide 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; Flecainide belongs to Cardiovascular.
Why it happens
Cobicistat inhibits CYP2D6 and CYP3A4, reducing flecainide clearance.
What to do
Avoid the combination where possible, or reduce the flecainide dose and monitor ECG closely and flecainide levels. Consider an alternative antiarrhythmic or antiretroviral.
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 Flecainide
- Flecainide + Nirmatrelvir Contraindicated
- Flecainide + Nirmatrelvir / ritonavir Contraindicated
- Flecainide + Pimozide Contraindicated
- Flecainide + Ritonavir Contraindicated
- Flecainide + Thioridazine Contraindicated
- Flecainide + Tipranavir 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 Flecainide?
MediHelp rates the interaction as major. Cobicistat and Flecainide 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 CYP2D6 as well as CYP3A4 and can increase flecainide concentrations. This raises the risk of conduction abnormalities and ventricular arrhythmias.
How serious is the interaction between Cobicistat and Flecainide?
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 reduce the flecainide dose and monitor ECG closely and flecainide levels. Consider an alternative antiarrhythmic or antiretroviral.
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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