Drug interactions
Colesevelam + Phenytoin
Severity: Moderate
Colesevelam and Phenytoin: moderate 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
Colesevelam is a bile acid sequestrant that can bind phenytoin in the gut and reduce how much is absorbed. This may lower phenytoin concentrations and increase the risk of breakthrough seizures.
What this interaction means in plain words
Colesevelam and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Colesevelam belongs to Endocrine; Phenytoin belongs to Central Nervous System.
Why it happens
Colesevelam binds phenytoin in the gastrointestinal tract, reducing its oral absorption.
What to do
Give oral phenytoin at least 4 hours before colesevelam. Monitor phenytoin serum levels and seizure control if the regimen is changed.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Colesevelam
- Amlodipine-olmesartan-hydrochlorothiazide + Colesevelam Moderate
- Amlodipine-olmesartan + Colesevelam Moderate
- Chenodiol + Colesevelam Moderate
- Cholic acid + Colesevelam Moderate
- Colesevelam + Cyclosporin Moderate
- Colesevelam + Glibenclamide Moderate
Frequently asked questions
Can I take Colesevelam with Phenytoin?
MediHelp rates the interaction as moderate. Colesevelam and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Colesevelam is a bile acid sequestrant that can bind phenytoin in the gut and reduce how much is absorbed. This may lower phenytoin concentrations and increase the risk of breakthrough seizures.
How serious is the interaction between Colesevelam and Phenytoin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Give oral phenytoin at least 4 hours before colesevelam. Monitor phenytoin serum levels and seizure control if the regimen is changed.
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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