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Exemestane

AEMPS

Steroidal aromatase inhibitors

ATC code: L02BG06

Brand names: Aromasin, Exemestano Cinfa, Exemestano Desgen

Updated · Methodology

Indications

A

ER-positive breast cancer

First line

Adjuvant therapy of early ER+ breast cancer in postmenopausal women and treatment of metastatic disease. Per ESMO 2024 and Spanish SEOM 2023 exemestane is used as first-line or as a switch after 2–3 years of tamoxifen (TEAM, BIG 1–98). Dose 25 mg once daily after meals. Adjuvant duration – 5 years (with or without tamoxifen). In metastatic disease – until progression with switch to letrozole or fulvestrant. Alternatives – anastrozole, letrozole.

Sources

  1. AEMPS: Ficha técnica de Exemestano (2024)
  2. N Engl J Med: A randomized trial of exemestane after two to three years of tamoxifen therapy in postmenopausal women with primary breast cancer. (2004)
  3. Lancet: Aromatase inhibitors versus tamoxifen in early breast cancer: patient-level meta-analysis of the randomised trials. (2015)
  4. Lancet: Adjuvant tamoxifen and exemestane in early breast cancer (TEAM): a randomised phase 3 trial. (2011)

ICD-10: C50 · ICD-11: 2C6Z

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

F

Athletic endurance

Not recommended

Exemestane is used by amateur bodybuilders and AAS users as a steroidal aromatase inhibitor. ASCO 2022 and the AEMPS Ficha Técnica confine exemestane to hormone-receptor-positive breast cancer in postmenopausal women. Approved indications in male athletes do not exist. Use causes marked bone mineral density loss, arthralgia, hypertension and psychiatric effects.

Sources

  1. AEMPS: Ficha técnica de Exemestano (2024)
  2. ISSN: International Society of Sports Nutrition position stand: creatine supplementation (2017)
How to read tiers A–F
  • AStrong evidence – first or second line in international guidelines
  • BRecommended in selected cases
  • CStudy data contradict each other
  • DBenefit not proven, no documented harm
  • FDocumented harm, or risk without benefit

Mechanism of action

Irreversible third-generation steroidal aromatase inhibitor. Blocks the aromatase enzyme (CYP19) that converts androgens (testosterone, androstenedione) into estrogens (estradiol, estrone) in peripheral tissues – fat, muscle, tumor. In postmenopausal women this peripheral pathway becomes the main estrogen source after ovarian function ceases. Unlike reversible non-steroidal inhibitors (anastrozole, letrozole), exemestane binds aromatase irreversibly.

Safety

Contraindications

  • Hypersensitivity
  • Pre- and perimenopausal status
  • Pregnancy and lactation
  • Severe hepatic or renal impairment

Serious adverse effects

  • Osteoporosis and fractures on long-term therapy
  • Cardiovascular events (LDL elevation)
  • Hepatotoxicity

Common adverse effects

  • Hot flashes
  • Joint pain
  • Fatigue
  • Insomnia
  • Sweating
  • BMD reduction

Pregnancy: can you take Exemestane?

AEMPS summary of product characteristics (section 4.6): there are no clinical data on exemestane exposure in pregnant women, and animal studies have shown reproductive toxicity. Exemestane is therefore contraindicated in pregnant women.

Breastfeeding: can you take Exemestane?

Contraindicated during lactation.

Calculate RIDFull profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Timing and administration

Take after meals for better absorption (unlike abiraterone). Adjuvant duration – 5 years. Monitor bone mineral density (DEXA) before start and every 1–2 years – osteoporosis and fracture risk higher than tamoxifen. Add calcium 1000–1200 mg and vitamin D 800–1000 IU daily. For osteoporosis – bisphosphonates or denosumab. Lipid profile every 6 months.

Drug interactions

Strong CYP3A4 inducers (rifampicin, phenytoin, carbamazepine, St John's wort) reduce efficacy – avoid. CYP3A4 inhibitors (clarithromycin, ketoconazole, ritonavir) have no clinically significant effect. Estrogenic preparations (including high-dose phytoestrogen supplements) are contraindicated – counteract the effect.
Label mentions10 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

  • MajorCarbamazepine
    «DRUG INTERACTIONS: Co-medications that induce CYP 3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. John's wort) may significantly decrease exposure to EXEMESTANE. Dose…»

    FDA, section 7 · Open on DailyMed

  • MajorPhenobarbital
    «DRUG INTERACTIONS: Co-medications that induce CYP 3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. John's wort) may significantly decrease exposure to EXEMESTANE. Dose…»

    FDA, section 7 · Open on DailyMed

  • MajorPhenytoin
    «DRUG INTERACTIONS: Co-medications that induce CYP 3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. John's wort) may significantly decrease exposure to EXEMESTANE. Dose…»

    FDA, section 7 · Open on DailyMed

  • MajorRifampicin
    «DRUG INTERACTIONS: Co-medications that induce CYP 3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. John's wort) may significantly decrease exposure to EXEMESTANE. Dose…»

    FDA, section 7 · Open on DailyMed

  • ModerateCYP3A4 inducersclass named in the label
    «DRUG INTERACTIONS: Co-medications that induce CYP 3A4 (e.g., rifampicin, phenytoin, carbamazepine, phenobarbital, or St. John's wort) may significantly decrease exposure to EXEMESTANE. Dose…»

    FDA, section 7 · Open on DailyMed

  • antiepilépticosclass named in the label
    «En un estudio de interacción con rifampicina, un potente inductor de CYP450, a una dosis de 600 mg al día y una dosis única de exemestano de 25 mg, el AUC de exemestano se redujo en un 54% y la C máx…»

    AEMPS, section 4.5 · Open on CIMA

  • Carbamazepine
    «En un estudio de interacción con rifampicina, un potente inductor de CYP450, a una dosis de 600 mg al día y una dosis única de exemestano de 25 mg, el AUC de exemestano se redujo en un 54% y la C máx…»

    AEMPS, section 4.5 · Open on CIMA

  • Ketoconazole
    «Los datos obtenidos in vitro muestran que el medicamento se metaboliza a través del citocromo P450 (CYP) 3A4 y las aldocetorreductasas (ver sección 5.2) y no inhibe ninguna de las principales…»

    AEMPS, section 4.5 · Open on CIMA

  • Phenytoin
    «En un estudio de interacción con rifampicina, un potente inductor de CYP450, a una dosis de 600 mg al día y una dosis única de exemestano de 25 mg, el AUC de exemestano se redujo en un 54% y la C máx…»

    AEMPS, section 4.5 · Open on CIMA

  • Rifampicin
    «En un estudio de interacción con rifampicina, un potente inductor de CYP450, a una dosis de 600 mg al día y una dosis única de exemestano de 25 mg, el AUC de exemestano se redujo en un 54% y la C máx…»

    AEMPS, section 4.5 · Open on CIMA

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Frequently asked

What is Exemestane used for?

Exemestane is evaluated for the following indications with varying evidence strength: ER-positive breast cancer (evidence tier A), Athletic endurance (evidence tier F). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Exemestane?

Common side effects of Exemestane (≥ 1 in 100): Hot flashes, Joint pain, Fatigue, Insomnia, Sweating, BMD reduction. See the Safety section for uncommon and serious reactions.

Is Exemestane safe during pregnancy?

AEMPS summary of product characteristics (section 4.6): there are no clinical data on exemestane exposure in pregnant women, and animal studies have shown reproductive toxicity. Exemestane is therefore contraindicated in pregnant women.

Is Exemestane compatible with breastfeeding?

Contraindicated during lactation.

Who should not take Exemestane?

Exemestane is contraindicated in: Hypersensitivity; Pre- and perimenopausal status; Pregnancy and lactation; Severe hepatic or renal impairment. Full list in the Safety section.

Official sources

Direct links to regulator labels. Open in a new tab.

Other drugs in this group

Abiraterone, Anastrozole, Bicalutamide, Letrozole, Tamoxifen