Drug interactions
Avanafil + Fosphenytoin
Severity: Moderate
Avanafil 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, via phenytoin, induces CYP3A4 and may lower avanafil concentrations. Erectile response may be diminished.
What this interaction means in plain words
Avanafil 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.
Avanafil belongs to Genitourinary; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin-mediated induction of CYP3A4 increases avanafil metabolism.
What to do
Monitor erectile response and consider an alternative therapy if avanafil is ineffective, without exceeding the labeled maximum dose.
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 Avanafil
- Amyl nitrite + Avanafil Contraindicated
- Atazanavir + Avanafil Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Avanafil + Conivaptan Contraindicated
- Avanafil + Darunavir Contraindicated
- Avanafil + Fosamprenavir 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 Avanafil with Fosphenytoin?
MediHelp rates the interaction as moderate. Avanafil 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, via phenytoin, induces CYP3A4 and may lower avanafil concentrations. Erectile response may be diminished.
How serious is the interaction between Avanafil 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 erectile response and consider an alternative therapy if avanafil is ineffective, without exceeding the labeled maximum dose.
What other medicines interact with Avanafil?
MediHelp also lists interactions of Avanafil with, for example, Amyl nitrite, Atazanavir, Clarithromycin. The full list is on the Avanafil page.
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