Drug interactions
Buprenorphine + Fosphenytoin
Severity: Moderate
Buprenorphine and Fosphenytoin: 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
Phenytoin, the active form of fosphenytoin, induces CYP3A4 and can lower buprenorphine concentrations, leading to withdrawal symptoms or reduced analgesia. Both agents can also contribute to sedation.
What this interaction means in plain words
Buprenorphine and Fosphenytoin 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.
Buprenorphine belongs to Musculoskeletal; Fosphenytoin belongs to Central Nervous System.
Why it happens
CYP3A4 induction by phenytoin increases buprenorphine clearance.
What to do
Monitor for opioid withdrawal or inadequate pain control and increase the buprenorphine dose as needed. Re-evaluate the dose if fosphenytoin is stopped.
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 Buprenorphine
- Alvimopan + Buprenorphine Contraindicated
- Buprenorphine + Calcium / magnesium / potassium / sodium oxybates Contraindicated
- Buprenorphine + Olanzapine / samidorphan Contraindicated
- Buprenorphine + Phenelzine Contraindicated
- Buprenorphine + Pimozide Contraindicated
- Buprenorphine + Thioridazine Contraindicated
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Buprenorphine with Fosphenytoin?
MediHelp rates the interaction as moderate. Buprenorphine and Fosphenytoin 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. Phenytoin, the active form of fosphenytoin, induces CYP3A4 and can lower buprenorphine concentrations, leading to withdrawal symptoms or reduced analgesia. Both agents can also contribute to sedation.
How serious is the interaction between Buprenorphine and Fosphenytoin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for opioid withdrawal or inadequate pain control and increase the buprenorphine dose as needed. Re-evaluate the dose if fosphenytoin is stopped.
What other medicines interact with Buprenorphine?
MediHelp also lists interactions of Buprenorphine with, for example, Alvimopan, Calcium / magnesium / potassium / sodium oxybates, Olanzapine / samidorphan. The full list is on the Buprenorphine page.
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