Drug interactions
Fosphenytoin + Zaleplon
Severity: Minor
Fosphenytoin and Zaleplon: minor 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, an inducer of CYP3A4 and other enzymes, which can reduce zaleplon exposure. Strong inducers such as phenytoin may reduce hypnotic efficacy, since zaleplon has a short duration and low baseline exposure.
What this interaction means in plain words
Fosphenytoin and Zaleplon have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fosphenytoin belongs to Central Nervous System; Zaleplon belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 (and other enzymes), accelerating zaleplon clearance.
What to do
Monitor for reduced hypnotic effect and consider an alternative sleep agent if zaleplon becomes ineffective; do not exceed the labeled maximum dose.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Zaleplon
- Calcium / magnesium / potassium / sodium oxybates + Zaleplon Contraindicated
- Sodium oxybate + Zaleplon Contraindicated
- Brexanolone + Zaleplon Major
- Buprenorphine long-acting + Zaleplon Major
- Buprenorphine subdermal implant + Zaleplon Major
- Buprenorphine transdermal + Zaleplon Major
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 Fosphenytoin with Zaleplon?
MediHelp rates the interaction as minor. Fosphenytoin and Zaleplon have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Fosphenytoin is converted to phenytoin, an inducer of CYP3A4 and other enzymes, which can reduce zaleplon exposure. Strong inducers such as phenytoin may reduce hypnotic efficacy, since zaleplon has a short duration and low baseline exposure.
How serious is the interaction between Fosphenytoin and Zaleplon?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for reduced hypnotic effect and consider an alternative sleep agent if zaleplon becomes ineffective; do not exceed the labeled maximum dose.
What other medicines interact with Zaleplon?
MediHelp also lists interactions of Zaleplon with, for example, Calcium / magnesium / potassium / sodium oxybates, Sodium oxybate, Brexanolone. The full list is on the Zaleplon page.
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