Drug interactions
Morphine + Olanzapine / samidorphan
Severity: Contraindicated
Morphine and Olanzapine / samidorphan: contraindicated 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
Samidorphan is an opioid antagonist that blocks morphine's effect and can precipitate acute withdrawal in opioid-dependent patients. Patients on opioids who start the combination may also have reduced analgesia.
What this interaction means in plain words
Morphine and Olanzapine / samidorphan are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Why it happens
Pharmacodynamic antagonism at opioid receptors by samidorphan.
What to do
Do not start in patients using opioids; ensure an opioid-free interval of at least 7 days for short-acting opioids before starting. Use an alternative antipsychotic if opioids are required.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Morphine
- Alvimopan + Morphine Contraindicated
- Isocarboxazid + Morphine Contraindicated
- Morphine + Phenelzine Contraindicated
- Morphine + Tranylcypromine Contraindicated
- Alfentanil + Morphine Major
- Alprazolam + Morphine Major
Frequently asked questions
Can I take Morphine with Olanzapine / samidorphan?
MediHelp rates the interaction as contraindicated. Morphine and Olanzapine / samidorphan are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Samidorphan is an opioid antagonist that blocks morphine's effect and can precipitate acute withdrawal in opioid-dependent patients. Patients on opioids who start the combination may also have reduced analgesia.
How serious is the interaction between Morphine and Olanzapine / samidorphan?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not start in patients using opioids; ensure an opioid-free interval of at least 7 days for short-acting opioids before starting. Use an alternative antipsychotic if opioids are required.
What other medicines interact with Morphine?
MediHelp also lists interactions of Morphine with, for example, Alvimopan, Isocarboxazid, Phenelzine. The full list is on the Morphine page.
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