Drug interactions
Naldemedine + Phenytoin
Severity: Major
Naldemedine and Phenytoin: 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
Phenytoin may substantially reduce naldemedine exposure, leading to loss of its effect on opioid-induced constipation.
What this interaction means in plain words
Naldemedine and Phenytoin 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.
Naldemedine belongs to Gastrointestinal Tract; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, which metabolizes naldemedine, and may also induce P-glycoprotein.
What to do
Avoid the combination per labeling. Use an alternative laxative approach if phenytoin is required.
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 Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Other interactions of Naldemedine
- Bupropion-naltrexone + Naldemedine Major
- Naldemedine + Naltrexone Major
- Naldemedine + Rifampicin Major
- Amobarbital + Naldemedine Moderate
- Apalutamide + Naldemedine Moderate
- Aprepitant + Naldemedine Moderate
Frequently asked questions
Can I take Naldemedine with Phenytoin?
MediHelp rates the interaction as major. Naldemedine and Phenytoin 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. Phenytoin may substantially reduce naldemedine exposure, leading to loss of its effect on opioid-induced constipation.
How serious is the interaction between Naldemedine and Phenytoin?
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 the combination per labeling. Use an alternative laxative approach if phenytoin is required.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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