Drug interactions
Phenytoin + Pretomanid
Severity: Major
Phenytoin and Pretomanid: 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 is a strong inducer of CYP3A4 and may lower pretomanid exposure, risking reduced antimycobacterial activity and treatment failure. Both agents can also be hepatotoxic, so combined use may add to liver injury risk.
What this interaction means in plain words
Phenytoin and Pretomanid 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; Pretomanid belongs to Anti Bacterial.
Why it happens
Phenytoin induces CYP3A4-mediated metabolism of pretomanid, and both drugs have additive hepatotoxic potential.
What to do
Avoid the combination and switch the anticonvulsant to a non-inducing agent such as levetiracetam where feasible. If it cannot be avoided, monitor liver enzymes and treatment response closely.
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 Pretomanid
Frequently asked questions
Can I take Phenytoin with Pretomanid?
MediHelp rates the interaction as major. Phenytoin and Pretomanid 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 is a strong inducer of CYP3A4 and may lower pretomanid exposure, risking reduced antimycobacterial activity and treatment failure. Both agents can also be hepatotoxic, so combined use may add to liver injury risk.
How serious is the interaction between Phenytoin and Pretomanid?
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 and switch the anticonvulsant to a non-inducing agent such as levetiracetam where feasible. If it cannot be avoided, monitor liver enzymes and treatment response closely.
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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