Drug interactions
Diphenoxylate-atropine + Olanzapine / samidorphan
Severity: Major
Diphenoxylate-atropine and Olanzapine / samidorphan: 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
Samidorphan is an opioid antagonist and may block or reduce the effects of diphenoxylate, which is an opioid, and can precipitate withdrawal in opioid-dependent patients. Olanzapine also has antimuscarinic and sedating effects that add to atropine, increasing the risk of constipation, urinary retention and reduced gut motility.
What this interaction means in plain words
Diphenoxylate-atropine and Olanzapine / samidorphan 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
Opioid receptor antagonism by samidorphan opposes diphenoxylate, while olanzapine and atropine have additive antimuscarinic effects.
What to do
Avoid giving diphenoxylate-atropine with olanzapine/samidorphan where possible and use a non-opioid antidiarrheal instead. Monitor for reduced antidiarrheal effect, anticholinergic effects and bowel hypomotility.
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 Diphenoxylate-atropine
- Diphenoxylate-atropine + Isocarboxazid Contraindicated
- Diphenoxylate-atropine + Phenelzine Contraindicated
- Diphenoxylate-atropine + Tranylcypromine Contraindicated
- Alfentanil + Diphenoxylate-atropine Major
- Alvimopan + Diphenoxylate-atropine Major
- Amitriptyline + Diphenoxylate-atropine Major
Frequently asked questions
Can I take Diphenoxylate-atropine with Olanzapine / samidorphan?
MediHelp rates the interaction as major. Diphenoxylate-atropine and Olanzapine / samidorphan 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. Samidorphan is an opioid antagonist and may block or reduce the effects of diphenoxylate, which is an opioid, and can precipitate withdrawal in opioid-dependent patients. Olanzapine also has antimuscarinic and sedating effects that add to atropine, increasing the risk of constipation, urinary retention and reduced gut motility.
How serious is the interaction between Diphenoxylate-atropine and Olanzapine / samidorphan?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid giving diphenoxylate-atropine with olanzapine/samidorphan where possible and use a non-opioid antidiarrheal instead. Monitor for reduced antidiarrheal effect, anticholinergic effects and bowel hypomotility.
What other medicines interact with Diphenoxylate-atropine?
MediHelp also lists interactions of Diphenoxylate-atropine with, for example, Isocarboxazid, Phenelzine, Tranylcypromine. The full list is on the Diphenoxylate-atropine page.
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