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Drug interactions

Disopyramide + Methadone

Severity: Major

Disopyramide and Methadone: 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

Both drugs can prolong the QT interval, raising the risk of torsades de pointes and sudden death. Disopyramide is a class IA antiarrhythmic with a known proarrhythmic potential.

What this interaction means in plain words

Disopyramide and Methadone 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.

Disopyramide belongs to Cardiovascular; Methadone belongs to Musculoskeletal.

Evidence level: Moderate

Why it happens

Additive QT prolongation through cardiac potassium channel blockade.

What to do

Avoid if possible and choose an alternative antiarrhythmic. If used together, monitor ECG and keep potassium and magnesium normal.

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?

Bring a full list of your medicines, including over-the-counter products, supplements and herbal remedies, to every pharmacy visit.

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References

Frequently asked questions

Can I take Disopyramide with Methadone?

MediHelp rates the interaction as major. Disopyramide and Methadone 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, raising the risk of torsades de pointes and sudden death. Disopyramide is a class IA antiarrhythmic with a known proarrhythmic potential.

How serious is the interaction between Disopyramide and Methadone?

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 and choose an alternative antiarrhythmic. If used together, monitor ECG and keep potassium and magnesium normal.

What other medicines interact with Methadone?

MediHelp also lists interactions of Methadone with, for example, Alvimopan, Calcium / magnesium / potassium / sodium oxybates, Droperidol. The full list is on the Methadone page.

Full monographs, dosing and an interaction checker in the MediHelp app

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