Drug interactions
Dupilumab + Fosphenytoin
Severity: Moderate
Dupilumab and Fosphenytoin: 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
Dupilumab could restore CYP enzyme activity previously suppressed by inflammatory cytokines, altering clearance of phenytoin, the active form of fosphenytoin. Phenytoin has a narrow therapeutic index and nonlinear kinetics, so small changes in metabolism may matter. The interaction is predicted rather than demonstrated.
What this interaction means in plain words
Dupilumab and Fosphenytoin 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.
Dupilumab belongs to Respiratory; Fosphenytoin belongs to Central Nervous System.
Why it happens
Normalization of cytokine-suppressed CYP2C9/2C19 expression after IL-4 receptor blockade, potentially altering phenytoin clearance.
What to do
Check free or total phenytoin concentrations when dupilumab is started or stopped. Adjust the dose according to levels and seizure control.
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 Dupilumab
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Dupilumab with Fosphenytoin?
MediHelp rates the interaction as moderate. Dupilumab and Fosphenytoin 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. Dupilumab could restore CYP enzyme activity previously suppressed by inflammatory cytokines, altering clearance of phenytoin, the active form of fosphenytoin. Phenytoin has a narrow therapeutic index and nonlinear kinetics, so small changes in metabolism may matter. The interaction is predicted rather than demonstrated.
How serious is the interaction between Dupilumab and Fosphenytoin?
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 free or total phenytoin concentrations when dupilumab is started or stopped. Adjust the dose according to levels and seizure control.
What other medicines interact with Dupilumab?
MediHelp also lists interactions of Dupilumab with, for example, Smallpox vaccine live, Adenovirus types 4 and 7 live, Bcg vaccine live. The full list is on the Dupilumab page.
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