Drug interactions
Phenytoin + Sodium oxybate
Severity: Major
Phenytoin and Sodium oxybate: 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
Both agents depress the central nervous system, and combining them can cause profound sedation, respiratory depression, coma or death. Sodium oxybate also carries a boxed warning about concomitant CNS depressants.
What this interaction means in plain words
Phenytoin and Sodium oxybate 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 belongs to Central Nervous System; Sodium oxybate belongs to Central Nervous System.
Why it happens
Additive CNS and respiratory depression through pharmacodynamic synergy.
What to do
Avoid combining where alternatives exist. If necessary, use the lowest effective doses and monitor closely for sedation and respiratory depression.
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 Sodium oxybate
- Alprazolam + Sodium oxybate Contraindicated
- Amobarbital + Sodium oxybate Contraindicated
- Butorphanol + Sodium oxybate Contraindicated
- Chloral hydrate + Sodium oxybate Contraindicated
- Clonazepam + Sodium oxybate Contraindicated
- Clorazepate + Sodium oxybate Contraindicated
Frequently asked questions
Can I take Phenytoin with Sodium oxybate?
MediHelp rates the interaction as major. Phenytoin and Sodium oxybate 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. Both agents depress the central nervous system, and combining them can cause profound sedation, respiratory depression, coma or death. Sodium oxybate also carries a boxed warning about concomitant CNS depressants.
How serious is the interaction between Phenytoin and Sodium oxybate?
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 combining where alternatives exist. If necessary, use the lowest effective doses and monitor closely for sedation and respiratory depression.
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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