Drug interactions
Exemestane + Fosphenytoin
Severity: Moderate
Exemestane 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, is a strong CYP3A4 inducer and can lower exemestane concentrations. This may reduce its estrogen suppression and antitumor effect.
What this interaction means in plain words
Exemestane 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.
Exemestane belongs to Oncology; Fosphenytoin belongs to Central Nervous System.
Why it happens
Induction of CYP3A4 increases exemestane metabolism and clearance.
What to do
Use exemestane 50 mg daily after a meal when combined with a strong CYP3A4 inducer, as labeled, or choose a non-inducing anticonvulsant.
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 Exemestane
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 Exemestane with Fosphenytoin?
MediHelp rates the interaction as moderate. Exemestane 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, is a strong CYP3A4 inducer and can lower exemestane concentrations. This may reduce its estrogen suppression and antitumor effect.
How serious is the interaction between Exemestane 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: Use exemestane 50 mg daily after a meal when combined with a strong CYP3A4 inducer, as labeled, or choose a non-inducing anticonvulsant.
What other medicines interact with Exemestane?
MediHelp also lists interactions of Exemestane with, for example, Bazedoxifene-conjugated estrogens, Desogestrel-ethinyl estradiol, Estradiol. The full list is on the Exemestane page.
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