Drug interactions
Anastrozole + Toremifene
Severity: Moderate
Anastrozole and Toremifene: 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
Toremifene is an antiestrogen and anastrozole is an aromatase inhibitor, so combining them offers no therapeutic advantage in breast cancer. Pharmacokinetic data with the related drug tamoxifen showed reduced anastrozole exposure, and a similar effect is possible with toremifene. The combination is not recommended for adjuvant treatment.
What this interaction means in plain words
Anastrozole and Toremifene 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.
Anastrozole belongs to Oncology; Toremifene belongs to Endocrine.
Why it happens
Overlapping endocrine action without added benefit, with possible reduction of anastrozole levels by the antiestrogen; the CYP3A4 effect cited for anastrozole is not clinically relevant.
What to do
Avoid routine co-administration and choose one endocrine agent according to menopausal status and treatment guidelines. If used sequentially, monitor response and tolerance.
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 Anastrozole
- Anastrozole + Bazedoxifene / conjugated estrogens Contraindicated
- Anastrozole + Bazedoxifene-conjugated estrogens Contraindicated
- Anastrozole + Conjugated estrogens Contraindicated
- Anastrozole + Estradiol Contraindicated
- Anastrozole + Estrogens conjugated synthetic Contraindicated
- Anastrozole + Estrogens esterified Contraindicated
Other interactions of Toremifene
- Amiodarone + Toremifene Contraindicated
- Dronedarone + Toremifene Contraindicated
- Nilotinib + Toremifene Contraindicated
- Pimozide + Toremifene Contraindicated
- Quinidine + Toremifene Contraindicated
- Ribociclib + Toremifene Contraindicated
Frequently asked questions
Can I take Anastrozole with Toremifene?
MediHelp rates the interaction as moderate. Anastrozole and Toremifene 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. Toremifene is an antiestrogen and anastrozole is an aromatase inhibitor, so combining them offers no therapeutic advantage in breast cancer. Pharmacokinetic data with the related drug tamoxifen showed reduced anastrozole exposure, and a similar effect is possible with toremifene. The combination is not recommended for adjuvant treatment.
How serious is the interaction between Anastrozole and Toremifene?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid routine co-administration and choose one endocrine agent according to menopausal status and treatment guidelines. If used sequentially, monitor response and tolerance.
What other medicines interact with Anastrozole?
MediHelp also lists interactions of Anastrozole with, for example, Bazedoxifene / conjugated estrogens, Bazedoxifene-conjugated estrogens, Conjugated estrogens. The full list is on the Anastrozole page.
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