Drug interactions
Ethinyl estradiol-drospirenone + Letrozole
Severity: Major
Ethinyl estradiol-drospirenone and Letrozole: 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
Letrozole suppresses estrogen synthesis in postmenopausal women with hormone-receptor-positive breast cancer. Estrogen-containing contraceptives provide exogenous estrogen that can oppose this effect and may stimulate hormone-dependent tumor growth.
What this interaction means in plain words
Ethinyl estradiol-drospirenone and Letrozole 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.
Ethinyl estradiol-drospirenone belongs to Endocrine; Letrozole belongs to Oncology.
Why it happens
Pharmacodynamic antagonism: exogenous estrogen counteracts aromatase inhibition.
What to do
Avoid estrogen-containing products with letrozole. Use a non-hormonal contraceptive if one is needed in a premenopausal patient.
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-drospirenone
- Ethinyl estradiol-drospirenone + Fezolinetant Contraindicated
- Ethinyl estradiol-drospirenone + Ombitasvir / paritaprevir / ritonavir Contraindicated
- Ethinyl estradiol-drospirenone + Ombitasvir / paritaprevir / ritonavir and dasabuvir Contraindicated
- Ethinyl estradiol-drospirenone + Tranexamic acid Contraindicated
- Aminocaproic acid + Ethinyl estradiol-drospirenone Major
- Amobarbital + Ethinyl estradiol-drospirenone Major
Other interactions of Letrozole
Frequently asked questions
Can I take Ethinyl estradiol-drospirenone with Letrozole?
MediHelp rates the interaction as major. Ethinyl estradiol-drospirenone and Letrozole 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. Letrozole suppresses estrogen synthesis in postmenopausal women with hormone-receptor-positive breast cancer. Estrogen-containing contraceptives provide exogenous estrogen that can oppose this effect and may stimulate hormone-dependent tumor growth.
How serious is the interaction between Ethinyl estradiol-drospirenone and Letrozole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid estrogen-containing products with letrozole. Use a non-hormonal contraceptive if one is needed in a premenopausal patient.
What other medicines interact with Ethinyl estradiol-drospirenone?
MediHelp also lists interactions of Ethinyl estradiol-drospirenone with, for example, Fezolinetant, Ombitasvir / paritaprevir / ritonavir, Ombitasvir / paritaprevir / ritonavir and dasabuvir. The full list is on the Ethinyl estradiol-drospirenone page.
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