Drug interactions
Mexiletine + Ritonavir
Severity: Major
Mexiletine and Ritonavir: 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
Ritonavir inhibits CYP2D6 and CYP3A4 and can raise mexiletine concentrations. This increases the risk of neurotoxicity and serious arrhythmias with a narrow-therapeutic-index antiarrhythmic.
What this interaction means in plain words
Mexiletine and Ritonavir 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.
Mexiletine belongs to Cardiovascular; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir inhibition of CYP2D6 and CYP3A4 reduces mexiletine metabolism.
What to do
Avoid if possible; otherwise reduce the mexiletine dose and monitor ECG, serum levels and signs of toxicity such as nausea, dizziness and tremor.
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 Mexiletine
- Fezolinetant + Mexiletine Contraindicated
- Mexiletine + Pimozide Contraindicated
- Alosetron + Mexiletine Major
- Amiodarone + Mexiletine Major
- Clozapine + Mexiletine Major
- Cobicistat + Mexiletine Major
Other interactions of Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Mexiletine with Ritonavir?
MediHelp rates the interaction as major. Mexiletine and Ritonavir 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. Ritonavir inhibits CYP2D6 and CYP3A4 and can raise mexiletine concentrations. This increases the risk of neurotoxicity and serious arrhythmias with a narrow-therapeutic-index antiarrhythmic.
How serious is the interaction between Mexiletine and Ritonavir?
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 mexiletine dose and monitor ECG, serum levels and signs of toxicity such as nausea, dizziness and tremor.
What other medicines interact with Mexiletine?
MediHelp also lists interactions of Mexiletine with, for example, Fezolinetant, Pimozide, Alosetron. The full list is on the Mexiletine page.
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