Drug interactions
Phenytoin + Ranolazine
Severity: Contraindicated
Phenytoin and Ranolazine: contraindicated 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 a strong CYP3A4 inducer and substantially lowers ranolazine concentrations, which can lead to loss of antianginal effect. Ranolazine labeling contraindicates strong CYP3A inducers.
What this interaction means in plain words
Phenytoin and Ranolazine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Phenytoin belongs to Central Nervous System; Ranolazine belongs to Cardiovascular.
Why it happens
Induction of CYP3A4 and P-glycoprotein by phenytoin increases ranolazine clearance.
What to do
Do not use together; choose another antianginal such as a beta-blocker or calcium channel blocker. If phenytoin is essential, avoid ranolazine.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Ranolazine
- Adagrasib + Ranolazine Contraindicated
- Amobarbital + Ranolazine Contraindicated
- Apalutamide + Ranolazine Contraindicated
- Butabarbital + Ranolazine Contraindicated
- Carbamazepine + Ranolazine Contraindicated
- Clarithromycin + Ranolazine Contraindicated
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 Ranolazine?
MediHelp rates the interaction as contraindicated. Phenytoin and Ranolazine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Phenytoin is a strong CYP3A4 inducer and substantially lowers ranolazine concentrations, which can lead to loss of antianginal effect. Ranolazine labeling contraindicates strong CYP3A inducers.
How serious is the interaction between Phenytoin and Ranolazine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not use together; choose another antianginal such as a beta-blocker or calcium channel blocker. If phenytoin is essential, avoid ranolazine.
What other medicines interact with Ranolazine?
MediHelp also lists interactions of Ranolazine with, for example, Adagrasib, Amobarbital, Apalutamide. The full list is on the Ranolazine page.
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