Drug interactions
Methadone + Solifenacin
Severity: Moderate
Methadone and Solifenacin: 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
Methadone causes dose-related QT prolongation and torsades de pointes, and solifenacin may add a small effect. Both also slow gastrointestinal and bladder function, so constipation and urinary retention may be worsened.
What this interaction means in plain words
Methadone and Solifenacin 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.
Methadone belongs to Musculoskeletal; Solifenacin belongs to Genitourinary.
Why it happens
Additive QT prolongation plus additive antimuscarinic and opioid effects on smooth muscle.
What to do
Monitor the ECG, especially with higher methadone doses, and correct electrolytes. Watch for urinary retention and constipation.
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 Solifenacin
Other interactions of Methadone
- Alvimopan + Methadone Contraindicated
- Calcium / magnesium / potassium / sodium oxybates + Methadone Contraindicated
- Droperidol + Methadone Contraindicated
- Ibutilide + Methadone Contraindicated
- Isocarboxazid + Methadone Contraindicated
- Lefamulin + Methadone Contraindicated
Frequently asked questions
Can I take Methadone with Solifenacin?
MediHelp rates the interaction as moderate. Methadone and Solifenacin 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. Methadone causes dose-related QT prolongation and torsades de pointes, and solifenacin may add a small effect. Both also slow gastrointestinal and bladder function, so constipation and urinary retention may be worsened.
How serious is the interaction between Methadone and Solifenacin?
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 the ECG, especially with higher methadone doses, and correct electrolytes. Watch for urinary retention and constipation.
What other medicines interact with Solifenacin?
MediHelp also lists interactions of Solifenacin with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Solifenacin page.
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