Drug interactions
Methadone + Saquinavir
Severity: Major
Methadone and Saquinavir: 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
Saquinavir can raise methadone concentrations and both drugs prolong the QT interval. The result may be opioid toxicity such as sedation and respiratory depression, along with an increased risk of torsades de pointes.
What this interaction means in plain words
Methadone and Saquinavir 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.
Why it happens
Saquinavir inhibits CYP3A4 and raises methadone exposure, and both drugs independently prolong QT.
What to do
Obtain a baseline ECG and monitor QTc, and watch for signs of methadone excess, reducing the dose if needed. Avoid use in patients with existing QT prolongation or electrolyte disturbances.
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 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 Saquinavir?
MediHelp rates the interaction as major. Methadone and Saquinavir 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. Saquinavir can raise methadone concentrations and both drugs prolong the QT interval. The result may be opioid toxicity such as sedation and respiratory depression, along with an increased risk of torsades de pointes.
How serious is the interaction between Methadone and Saquinavir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG and monitor QTc, and watch for signs of methadone excess, reducing the dose if needed. Avoid use in patients with existing QT prolongation or electrolyte disturbances.
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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