Drug interactions
Meperidine + Nirmatrelvir / ritonavir
Severity: Major
Meperidine and Nirmatrelvir / ritonavir: major 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
Ritonavir strongly inhibits CYP3A4 and may increase meperidine exposure, raising the risk of sedation and respiratory depression. Ritonavir has also been associated with increased normeperidine-related neurotoxicity concerns, and the labeling advises avoiding the combination.
What this interaction means in plain words
Meperidine and Nirmatrelvir / 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.
Why it happens
Ritonavir inhibits CYP3A4-mediated metabolism of meperidine.
What to do
Choose an alternative analgesic that is not dependent on CYP3A4 during the 5-day course. If unavoidable, use the lowest effective meperidine dose with close respiratory and sedation monitoring.
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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Other interactions of Meperidine
- Alvimopan + Meperidine Contraindicated
- Isocarboxazid + Meperidine Contraindicated
- Meperidine + Methylene blue Contraindicated
- Meperidine + Olanzapine / samidorphan Contraindicated
- Meperidine + Phenelzine Contraindicated
- Meperidine + Procarbazine Contraindicated
Frequently asked questions
Can I take Meperidine with Nirmatrelvir / ritonavir?
MediHelp rates the interaction as major. Meperidine and Nirmatrelvir / 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 strongly inhibits CYP3A4 and may increase meperidine exposure, raising the risk of sedation and respiratory depression. Ritonavir has also been associated with increased normeperidine-related neurotoxicity concerns, and the labeling advises avoiding the combination.
How serious is the interaction between Meperidine and Nirmatrelvir / 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: Choose an alternative analgesic that is not dependent on CYP3A4 during the 5-day course. If unavoidable, use the lowest effective meperidine dose with close respiratory and sedation monitoring.
What other medicines interact with Meperidine?
MediHelp also lists interactions of Meperidine with, for example, Alvimopan, Isocarboxazid, Methylene blue. The full list is on the Meperidine page.
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