Drug interactions
Fenfluramine + Methadone
Severity: Moderate
Fenfluramine and Methadone: 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
Fenfluramine is a serotonergic drug used for seizures in Dravet and Lennox-Gastaut syndromes, and it can cause somnolence. Used with methadone, additive sedation is possible, and combined serotonergic effects are theoretical.
What this interaction means in plain words
Fenfluramine and Methadone 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.
Fenfluramine belongs to Central Nervous System; Methadone belongs to Musculoskeletal.
Why it happens
Possible additive central nervous system depression; serotonergic effects of both drugs may add, though not well established.
What to do
Monitor for excessive sedation and for signs of serotonin toxicity such as agitation, tremor or hyperthermia. Adjust doses if symptoms develop.
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 Methadone
- Alvimopan + Methadone Contraindicated
- Calcium / magnesium / potassium / sodium oxybates + Methadone Contraindicated
- Droperidol + Methadone Contraindicated
- Ibutilide + Methadone Contraindicated
- Isocarboxazid + Methadone Contraindicated
- Lefamulin + Methadone Contraindicated
Other interactions of Fenfluramine
- Fenfluramine + Isocarboxazid Contraindicated
- Fenfluramine + Linezolid Contraindicated
- Fenfluramine + Phenelzine Contraindicated
- Fenfluramine + Selegiline Contraindicated
- Fenfluramine + Tranylcypromine Contraindicated
- Almotriptan + Fenfluramine Major
Frequently asked questions
Can I take Fenfluramine with Methadone?
MediHelp rates the interaction as moderate. Fenfluramine and Methadone 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. Fenfluramine is a serotonergic drug used for seizures in Dravet and Lennox-Gastaut syndromes, and it can cause somnolence. Used with methadone, additive sedation is possible, and combined serotonergic effects are theoretical.
How serious is the interaction between Fenfluramine and Methadone?
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 for excessive sedation and for signs of serotonin toxicity such as agitation, tremor or hyperthermia. Adjust doses if symptoms develop.
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.
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