Drug interactions
Estradiol + Fosamprenavir
Severity: Moderate
Estradiol and Fosamprenavir: 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
Ritonavir-boosted fosamprenavir has mixed inhibitory and inducing effects on estrogen metabolism, so estradiol levels can change unpredictably. Hormonal contraceptive efficacy may be affected and liver enzyme elevations have been reported with some combinations.
What this interaction means in plain words
Estradiol and Fosamprenavir 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.
Why it happens
Mixed CYP3A4 inhibition and induction of other estrogen metabolic pathways by amprenavir and ritonavir.
What to do
Use a non-hormonal contraceptive method if contraception is needed. Monitor for altered estrogen effect and adjust the estradiol dose by clinical response.
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 Estradiol
- Anastrozole + Estradiol Contraindicated
- Estradiol + Fezolinetant Contraindicated
- Estradiol + Ospemifene Contraindicated
- Antithrombin alfa + Estradiol Major
- Antithrombin iii + Estradiol Major
- Estradiol + Exemestane Major
Frequently asked questions
Can I take Estradiol with Fosamprenavir?
MediHelp rates the interaction as moderate. Estradiol and Fosamprenavir 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. Ritonavir-boosted fosamprenavir has mixed inhibitory and inducing effects on estrogen metabolism, so estradiol levels can change unpredictably. Hormonal contraceptive efficacy may be affected and liver enzyme elevations have been reported with some combinations.
How serious is the interaction between Estradiol and Fosamprenavir?
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 a non-hormonal contraceptive method if contraception is needed. Monitor for altered estrogen effect and adjust the estradiol dose by clinical response.
What other medicines interact with Estradiol?
MediHelp also lists interactions of Estradiol with, for example, Anastrozole, Fezolinetant, Ospemifene. The full list is on the Estradiol page.
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