Drug interactions
Diphenoxylate-atropine + Primidone
Severity: Major
Diphenoxylate-atropine and Primidone: 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
Primidone is metabolized to phenobarbital and is sedating, so with diphenoxylate it can increase drowsiness and respiratory depression. Risk is higher at larger doses and in older or debilitated patients.
What this interaction means in plain words
Diphenoxylate-atropine and Primidone 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.
Diphenoxylate-atropine belongs to Gastrointestinal Tract; Primidone belongs to Central Nervous System.
Why it happens
Additive CNS depression from barbiturate-type GABAergic action and opioid agonism.
What to do
Avoid combined use where possible; otherwise use low doses and monitor sedation and breathing. Counsel against alcohol and driving.
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
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Diphenoxylate-atropine with Primidone?
MediHelp rates the interaction as major. Diphenoxylate-atropine and Primidone 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. Primidone is metabolized to phenobarbital and is sedating, so with diphenoxylate it can increase drowsiness and respiratory depression. Risk is higher at larger doses and in older or debilitated patients.
How serious is the interaction between Diphenoxylate-atropine and Primidone?
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 combined use where possible; otherwise use low doses and monitor sedation and breathing. Counsel against alcohol and driving.
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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