Drug interactions
Phenytoin + Ticlopidine
Severity: Major
Phenytoin and Ticlopidine: major 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
Ticlopidine inhibits phenytoin metabolism, which can raise phenytoin concentrations to toxic levels, with nystagmus, ataxia and drowsiness. This has been described in case reports.
What this interaction means in plain words
Phenytoin and Ticlopidine 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 belongs to Central Nervous System; Ticlopidine belongs to Cardiovascular.
Why it happens
Inhibition of CYP2C9 and CYP2C19 metabolism of phenytoin by ticlopidine.
What to do
Check phenytoin levels when ticlopidine is started or stopped and reduce phenytoin dose as needed. Monitor for signs of toxicity.
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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Other interactions of Ticlopidine
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 Ticlopidine?
MediHelp rates the interaction as major. Phenytoin and Ticlopidine 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. Ticlopidine inhibits phenytoin metabolism, which can raise phenytoin concentrations to toxic levels, with nystagmus, ataxia and drowsiness. This has been described in case reports.
How serious is the interaction between Phenytoin and Ticlopidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check phenytoin levels when ticlopidine is started or stopped and reduce phenytoin dose as needed. Monitor for signs of toxicity.
What other medicines interact with Ticlopidine?
MediHelp also lists interactions of Ticlopidine with, for example, Mavacamten, Abrocitinib, Acetylsalicylic acid. The full list is on the Ticlopidine page.
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