Drug interactions
Ambrisentan + Phenytoin
Severity: Minor
Ambrisentan and Phenytoin: 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 is an enzyme inducer and could lower ambrisentan concentrations. Studies of other strong inducers such as rifampicin showed no clinically meaningful effect on ambrisentan, so the effect is likely small.
What this interaction means in plain words
Ambrisentan and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Ambrisentan belongs to Miscellaneous; Phenytoin belongs to Central Nervous System.
Why it happens
Possible induction of ambrisentan metabolism (CYP3A4, UGT) by phenytoin.
What to do
No routine dose change is needed. Monitor clinical response in pulmonary arterial hypertension if phenytoin is added.
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
Other interactions of Ambrisentan
- Ambrisentan + Apalutamide Moderate
- Ambrisentan + Bosentan Moderate
- Ambrisentan + Cyclosporin Moderate
- Ambrisentan + Amiodarone Minor
- Ambrisentan + Carbamazepine Minor
- Ambrisentan + Clarithromycin Minor
Frequently asked questions
Can I take Ambrisentan with Phenytoin?
MediHelp rates the interaction as minor. Ambrisentan and Phenytoin 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 is an enzyme inducer and could lower ambrisentan concentrations. Studies of other strong inducers such as rifampicin showed no clinically meaningful effect on ambrisentan, so the effect is likely small.
How serious is the interaction between Ambrisentan and Phenytoin?
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 routine dose change is needed. Monitor clinical response in pulmonary arterial hypertension if phenytoin is added.
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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