Drug interactions
Deflazacort + Phenytoin
Severity: Major
Deflazacort and Phenytoin: major interaction.
Last updated Sources: US FDA label
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 CYP3A4 inducer that speeds the conversion of deflazacort's active metabolite and lowers its exposure. This may lead to loss of efficacy of deflazacort.
What this interaction means in plain words
Deflazacort and Phenytoin 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.
Deflazacort belongs to Miscellaneous; Phenytoin belongs to Central Nervous System.
Why it happens
CYP3A4 induction by phenytoin increases clearance of deflazacort's active metabolite.
What to do
Avoid the combination; labeling advises against moderate or strong CYP3A4 inducers. Use a non-inducing anticonvulsant if possible.
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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References
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 Deflazacort
- Adenovirus types 4 and 7 live + Deflazacort Contraindicated
- Bcg vaccine live + Deflazacort Contraindicated
- Deflazacort + Influenza virus vaccine quadrivalent intranasal Contraindicated
- Deflazacort + Measles mumps and rubella vaccine Contraindicated
- Deflazacort + Measles mumps and rubella vaccine live Contraindicated
- Deflazacort + Measles mumps rubella and varicella vaccine live Contraindicated
Frequently asked questions
Can I take Deflazacort with Phenytoin?
MediHelp rates the interaction as major. Deflazacort and Phenytoin 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 CYP3A4 inducer that speeds the conversion of deflazacort's active metabolite and lowers its exposure. This may lead to loss of efficacy of deflazacort.
How serious is the interaction between Deflazacort and Phenytoin?
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; labeling advises against moderate or strong CYP3A4 inducers. Use a non-inducing anticonvulsant if possible.
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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