Drug interactions
Bictegravir + Phenytoin
Severity: Contraindicated
Bictegravir and Phenytoin: contraindicated 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 strongly induces CYP3A and UGT1A1, which can lower bictegravir concentrations considerably. This risks loss of virologic suppression and resistance.
What this interaction means in plain words
Bictegravir and Phenytoin are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Why it happens
Phenytoin induces CYP3A4 and UGT1A1, increasing bictegravir clearance.
What to do
Do not coadminister; change to a non-inducing antiseizure drug such as levetiracetam or use an alternative antiretroviral regimen.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
- Ensitrelvir + Phenytoin Contraindicated
Frequently asked questions
Can I take Bictegravir with Phenytoin?
MediHelp rates the interaction as contraindicated. Bictegravir and Phenytoin are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Phenytoin strongly induces CYP3A and UGT1A1, which can lower bictegravir concentrations considerably. This risks loss of virologic suppression and resistance.
How serious is the interaction between Bictegravir and Phenytoin?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not coadminister; change to a non-inducing antiseizure drug such as levetiracetam or use an alternative antiretroviral regimen.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Cabotegravir, Doravirine. The full list is on the Phenytoin page.
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