Drug interactions
Phenytoin + Ritlecitinib
Severity: Moderate
Phenytoin and Ritlecitinib: 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
Phenytoin may reduce ritlecitinib exposure, which could lead to reduced efficacy in alopecia areata.
What this interaction means in plain words
Phenytoin and Ritlecitinib 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; Ritlecitinib belongs to Oncology.
Why it happens
Phenytoin induces CYP3A4 (among other enzymes) involved in ritlecitinib clearance, lowering its plasma concentrations.
What to do
Monitor clinical response to ritlecitinib and consider a non-inducing antiseizure alternative if efficacy is lost.
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 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 Ritlecitinib
Frequently asked questions
Can I take Phenytoin with Ritlecitinib?
MediHelp rates the interaction as moderate. Phenytoin and Ritlecitinib 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 may reduce ritlecitinib exposure, which could lead to reduced efficacy in alopecia areata.
How serious is the interaction between Phenytoin and Ritlecitinib?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor clinical response to ritlecitinib and consider a non-inducing antiseizure alternative if efficacy is lost.
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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