Drug interactions
Phenytoin + Ustekinumab
Severity: Moderate
Phenytoin and Ustekinumab: moderate 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
Resolution of chronic inflammation with ustekinumab may restore CYP enzyme activity previously suppressed by cytokines. Phenytoin has a narrow therapeutic index and non-linear kinetics, so small changes in metabolism could alter levels. A clinically significant effect has not been well documented.
What this interaction means in plain words
Phenytoin and Ustekinumab can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Phenytoin belongs to Central Nervous System; Ustekinumab belongs to Gastrointestinal Tract.
Why it happens
Cytokine normalization may increase CYP2C9/2C19 expression and phenytoin clearance.
What to do
Check serum phenytoin concentration and seizure control when ustekinumab is started or discontinued, adjusting the dose as needed.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Ustekinumab
- Bcg vaccine live + Ustekinumab Contraindicated
- Typhoid vaccine live + Ustekinumab Contraindicated
- Adalimumab + Ustekinumab Major
- Adenovirus types 4 and 7 live + Ustekinumab Major
- Alefacept + Ustekinumab Major
- Anakinra + Ustekinumab Major
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
Frequently asked questions
Can I take Phenytoin with Ustekinumab?
MediHelp rates the interaction as moderate. Phenytoin and Ustekinumab can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Resolution of chronic inflammation with ustekinumab may restore CYP enzyme activity previously suppressed by cytokines. Phenytoin has a narrow therapeutic index and non-linear kinetics, so small changes in metabolism could alter levels. A clinically significant effect has not been well documented.
How serious is the interaction between Phenytoin and Ustekinumab?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check serum phenytoin concentration and seizure control when ustekinumab is started or discontinued, adjusting the dose as needed.
What other medicines interact with Ustekinumab?
MediHelp also lists interactions of Ustekinumab with, for example, Bcg vaccine live, Typhoid vaccine live, Adalimumab. The full list is on the Ustekinumab page.
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