Drug interactions
Phenytoin + Vilanterol / fluticasone furoate inhaled
Severity: Minor
Phenytoin and Vilanterol / fluticasone furoate inhaled: minor 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 induces CYP3A4, which is the main route of clearance for fluticasone furoate and a contributor to vilanterol clearance. Systemic exposure to both inhaled agents may fall, though inhaled doses give low systemic levels and the clinical impact is probably modest.
What this interaction means in plain words
Phenytoin and Vilanterol / fluticasone furoate inhaled have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Phenytoin induces CYP3A4-mediated metabolism of fluticasone furoate and vilanterol.
What to do
No dose change is usually needed; watch for loss of asthma or COPD control and reassess inhaled therapy if symptoms worsen after phenytoin is started.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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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
Frequently asked questions
Can I take Phenytoin with Vilanterol / fluticasone furoate inhaled?
MediHelp rates the interaction as minor. Phenytoin and Vilanterol / fluticasone furoate inhaled have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenytoin induces CYP3A4, which is the main route of clearance for fluticasone furoate and a contributor to vilanterol clearance. Systemic exposure to both inhaled agents may fall, though inhaled doses give low systemic levels and the clinical impact is probably modest.
How serious is the interaction between Phenytoin and Vilanterol / fluticasone furoate inhaled?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No dose change is usually needed; watch for loss of asthma or COPD control and reassess inhaled therapy if symptoms worsen after phenytoin is started.
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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