Drug interactions
Ethinyl estradiol-levonorgestrel + Fosamprenavir
Severity: Major
Ethinyl estradiol-levonorgestrel and Fosamprenavir: major 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
Fosamprenavir (amprenavir) coadministered with ethinyl estradiol/progestin contraceptives can change hormone levels and lower amprenavir exposure, with a risk of reduced virologic response and contraceptive failure. Ritonavir-boosted regimens add further variability.
What this interaction means in plain words
Ethinyl estradiol-levonorgestrel and Fosamprenavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Altered CYP3A4-mediated metabolism and possibly other pathways; the exact mechanism is not fully defined.
What to do
Use non-hormonal contraception instead of, or in addition to, the combined pill. Monitor HIV viral load if the combination is used.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Ethinyl estradiol-levonorgestrel
- Ethinyl estradiol-levonorgestrel + Fezolinetant Contraindicated
- Ethinyl estradiol-levonorgestrel + Ombitasvir / paritaprevir / ritonavir and dasabuvir Contraindicated
- Ethinyl estradiol-levonorgestrel + Tranexamic acid Contraindicated
- Aminocaproic acid + Ethinyl estradiol-levonorgestrel Major
- Amobarbital + Ethinyl estradiol-levonorgestrel Major
- Anastrozole + Ethinyl estradiol-levonorgestrel Major
Frequently asked questions
Can I take Ethinyl estradiol-levonorgestrel with Fosamprenavir?
MediHelp rates the interaction as major. Ethinyl estradiol-levonorgestrel and Fosamprenavir can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Fosamprenavir (amprenavir) coadministered with ethinyl estradiol/progestin contraceptives can change hormone levels and lower amprenavir exposure, with a risk of reduced virologic response and contraceptive failure. Ritonavir-boosted regimens add further variability.
How serious is the interaction between Ethinyl estradiol-levonorgestrel and Fosamprenavir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use non-hormonal contraception instead of, or in addition to, the combined pill. Monitor HIV viral load if the combination is used.
What other medicines interact with Ethinyl estradiol-levonorgestrel?
MediHelp also lists interactions of Ethinyl estradiol-levonorgestrel with, for example, Fezolinetant, Ombitasvir / paritaprevir / ritonavir and dasabuvir, Tranexamic acid. The full list is on the Ethinyl estradiol-levonorgestrel page.
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