Drug interactions
Buspirone + Fosphenytoin
Severity: Moderate
Buspirone 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
Fosphenytoin is converted to phenytoin, a CYP3A4 inducer, which can lower buspirone plasma concentrations. Anxiolytic benefit may be reduced or lost.
What this interaction means in plain words
Buspirone 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.
Buspirone belongs to Central Nervous System; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, increasing the first-pass and systemic metabolism of buspirone.
What to do
Assess anxiolytic response after starting or stopping fosphenytoin. Increase the buspirone dose if needed, and reduce it again if the inducer is withdrawn.
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 Buspirone
- Buspirone + Isocarboxazid Contraindicated
- Buspirone + Linezolid Contraindicated
- Buspirone + Phenelzine Contraindicated
- Buspirone + Procarbazine Contraindicated
- Buspirone + Selegiline Contraindicated
- Buspirone + Selegiline transdermal 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 Buspirone with Fosphenytoin?
MediHelp rates the interaction as moderate. Buspirone 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. Fosphenytoin is converted to phenytoin, a CYP3A4 inducer, which can lower buspirone plasma concentrations. Anxiolytic benefit may be reduced or lost.
How serious is the interaction between Buspirone 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: Assess anxiolytic response after starting or stopping fosphenytoin. Increase the buspirone dose if needed, and reduce it again if the inducer is withdrawn.
What other medicines interact with Buspirone?
MediHelp also lists interactions of Buspirone with, for example, Isocarboxazid, Linezolid, Phenelzine. The full list is on the Buspirone page.
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