Drug interactions
Fosphenytoin + Lurasidone
Severity: Contraindicated
Fosphenytoin and Lurasidone: 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
Fosphenytoin is converted to phenytoin, a strong CYP3A4 inducer that can reduce lurasidone exposure dramatically. This may lead to loss of antipsychotic efficacy and relapse. Strong inducers are contraindicated with lurasidone.
What this interaction means in plain words
Fosphenytoin and Lurasidone 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.
Fosphenytoin belongs to Central Nervous System; Lurasidone belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 by phenytoin increases lurasidone clearance.
What to do
Avoid the combination; use an alternative anticonvulsant or an antipsychotic not dependent on CYP3A4, and monitor psychiatric status.
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 Lurasidone
- Apalutamide + Lurasidone Contraindicated
- Atazanavir + Lurasidone Contraindicated
- Carbamazepine + Lurasidone Contraindicated
- Clarithromycin + Lurasidone Contraindicated
- Cobicistat + Lurasidone Contraindicated
- Conivaptan + Lurasidone Contraindicated
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Abiraterone + Fosphenytoin Major
Frequently asked questions
Can I take Fosphenytoin with Lurasidone?
MediHelp rates the interaction as contraindicated. Fosphenytoin and Lurasidone 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. Fosphenytoin is converted to phenytoin, a strong CYP3A4 inducer that can reduce lurasidone exposure dramatically. This may lead to loss of antipsychotic efficacy and relapse. Strong inducers are contraindicated with lurasidone.
How serious is the interaction between Fosphenytoin and Lurasidone?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination; use an alternative anticonvulsant or an antipsychotic not dependent on CYP3A4, and monitor psychiatric status.
What other medicines interact with Lurasidone?
MediHelp also lists interactions of Lurasidone with, for example, Apalutamide, Atazanavir, Carbamazepine. The full list is on the Lurasidone page.
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