Exemestane

updated

Exemestane is an FDA-approved medicine for postmenopausal women with estrogen-receptor-positive breast cancer, backed by the 4,724-woman IES trial and the 4,560-woman MAP.3 prevention trial. In males the record is one 10-day study in 12 healthy young males that measured hormones only (estradiol fell by 32 to 38% and testosterone rose by 56 to 60%), plus single-dose PK data. A PubMed search on 9 October 2026 found no study in men or steroid users of exemestane for gynecomastia, estradiol control or androgenic effects.

Steroidal aromatase inactivator

  • FDA approved AROMASIN (Pfizer) under NDA 020753 on 21 October 1999 for postmenopausal women with estrogen-receptor-positive breast cancer.
  • IES (4,724 postmenopausal women) found disease-free survival improved on switching from tamoxifen to exemestane (HR 0.69, 95% CI 0.58 to 0.82).
  • MAP.3 (4,560 postmenopausal women at increased risk) found invasive breast cancer in 11 versus 32 women at a median 35 months; prevention is not a labeled US indication.
  • In 12 healthy males aged 14 to 26, 10 days of exemestane lowered estradiol by 38% and 32% and raised testosterone by 60% and 56% at two doses; no clinical outcome was measured.
  • The label reports a mean terminal half-life of about 24 hours in healthy postmenopausal women. A separate study in young males found 8.9 hours.
  • The androgenic claim rests on receptor binding and breast cancer cell work on a metabolite; the label's endocrine data show testosterone rose only at 200 mg a day or more.

What is exemestane approved to do?

FDA approved AROMASIN (exemestane) on 21 October 1999 for postmenopausal women with estrogen-receptor-positive breast cancer. Use in men is not a labeled use.

The AROMASIN label covers postmenopausal women with estrogen-receptor-positive early breast cancer who switch to it after 2 to 3 years of tamoxifen to complete 5 years of adjuvant therapy, and advanced breast cancer that progressed on tamoxifen. Prevention, tested in MAP.3, is not a labeled US indication. The label version used here took effect on 24 December 2025.

FDA approved AROMASIN under NDA 020753 on 21 October 1999 (Pfizer). Approvals outside the United States are not covered here.

Exemestane is C20H24O2 (296.4 g/mol, CAS 107868-30-4, PubChem CID 60198), also named 6-methyleneandrosta-1,4-diene-3,17-dione. Label tablets contain exemestane itself, not a salt.

AROMASIN label, version effective 24 December 2025: indication, mechanism, PK, warnings

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

The label approves AROMASIN for postmenopausal women with estrogen-receptor-positive early breast cancer who switch to it after 2 to 3 years of tamoxifen to complete 5 years of adjuvant therapy, and for advanced breast cancer that progressed on tamoxifen. It calls exemestane an irreversible steroidal aromatase inactivator, similar in structure to androstenedione, that is processed to an intermediate binding the enzyme's active site (suicide inhibition). In postmenopausal women it suppressed circulating estrogens by at least 85% to 95% and whole-body aromatization by 98%; after one dose, maximal suppression came at 2 to 3 days and lasted 4 to 5 days. About 42% of a radiolabeled dose was absorbed, a high-fat breakfast raised AUC by 59% and Cmax by 39%, and the mean terminal half-life in healthy postmenopausal women is about 24 hours. Single-dose PK in fasted healthy men (mean age 32) was similar to that in fasted healthy postmenopausal women. Warnings cover bone loss (at 24 months lumbar spine bone mineral density fell 3.1% versus 0.2% on tamoxifen in IES, and 3.5% versus 2.4% on placebo in study 027), vitamin D assessment, avoiding systemic estrogen-containing agents, and embryo-fetal toxicity.

Participants / model
Postmenopausal women with breast cancer; healthy postmenopausal women and healthy men for PK
Treatment
AROMASIN oral tablets
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

The label's clinical data are in postmenopausal women. Its only male data are single-dose PK in healthy men.

Read the original source
Drugs@FDA: AROMASIN approved 21 October 1999

Regulatory record

U.S. Food and Drug Administration. Drugs@FDA application record for NDA 020753 (AROMASIN). Date read from the openFDA Drugs@FDA record.

FDA approved AROMASIN under NDA 020753 on 21 October 1999 (Pfizer).

Participants / model
Not a clinical population
Treatment
Drug application
Follow-up
Approved 1999
Study design
FDA application record
Funding
not stated in the source

This record gives the approval date and applicant. Indications come from the product label.

Read the original source
PubChem: exemestane identity

Chemical identity record

National Library of Medicine. PubChem compound record CID 60198 (exemestane).

Exemestane: PubChem CID 60198, C20H24O2, 296.4 g/mol, CAS 107868-30-4, also named 6-methyleneandrosta-1,4-diene-3,17-dione. Label tablets contain exemestane itself, not a salt.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only; it says nothing about efficacy or safety.

Read the original source
MAP.3: 4,560 women, invasive breast cancer 11 versus 32

Randomized controlled trial

Goss PE et al. N Engl J Med. 2011;364(25):2381-91. PMID 21639806.

At a median 35 months, invasive breast cancer occurred in 11 versus 32 women (annual incidence 0.19% versus 0.55%; HR 0.35, 95% CI 0.18 to 0.70). Adverse events occurred in 88% versus 85% (P = 0.003), with no significant differences in fractures, cardiovascular events, other cancers or treatment-related deaths.

Participants / model
4,560 postmenopausal women at moderately increased breast cancer risk
Treatment
Oral exemestane or placebo
Follow-up
Median follow-up 35 months
Study design
Randomized placebo-controlled trial (NCT00083174)
Funding
not stated in the source

Prevention is not a labeled US indication. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source

What did the large breast cancer trials find?

In IES, switching to exemestane after tamoxifen improved disease-free survival (HR 0.69) in 4,724 postmenopausal women. In MAP.3, exemestane cut invasive breast cancer from 32 to 11 cases in 4,560 women at increased risk.

The Intergroup Exemestane Study randomized 4,724 postmenopausal women who were disease-free after 2 to 3 years of adjuvant tamoxifen to switch to exemestane 25 mg or continue tamoxifen, completing 5 years in total. Disease-free survival improved with the switch (HR 0.69, 95% CI 0.58 to 0.82; hormone receptor-positive subgroup HR 0.65, 95% CI 0.53 to 0.79). At a median 119 months, overall survival did not differ significantly (467 deaths, 19.9%, versus 510, 21.5%).

MAP.3 randomized 4,560 postmenopausal women at moderately increased breast cancer risk to exemestane or placebo. At a median 35 months, invasive breast cancer occurred in 11 versus 32 women (annual incidence 0.19% versus 0.55%; HR 0.35, 95% CI 0.18 to 0.70). The trial is registered as NCT00083174. PubMed lists an erratum for the paper; the numbers here are from the abstract.

Both trials were in women. Neither describes men or steroid-cycle use.

IES: 4,724 postmenopausal women, switch to exemestane after tamoxifen

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) prescribing information, label version effective 24 December 2025, section 14.1 (Intergroup Exemestane Study). Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

IES randomized 4,724 postmenopausal women who were disease-free after 2 to 3 years of adjuvant tamoxifen to switch to exemestane or continue tamoxifen, completing 5 years in total. Disease-free survival improved with the switch (HR 0.69, 95% CI 0.58 to 0.82; hormone receptor-positive subgroup HR 0.65, 0.53 to 0.79). At a median 119 months, overall survival did not differ significantly (467 deaths, 19.9%, versus 510, 21.5%).

Participants / model
4,724 postmenopausal women with early breast cancer
Treatment
Oral exemestane 25 mg daily versus continued tamoxifen 20 or 30 mg daily
Follow-up
5 years of total adjuvant therapy; median follow-up 119 months for overall survival
Study design
Phase 3 randomized trial, results read from label section 14.1
Funding
not stated in the source

Women only. The result does not apply to men or to steroid-cycle use.

Read the original source
MAP.3: 4,560 women, invasive breast cancer 11 versus 32

Randomized controlled trial

Goss PE et al. N Engl J Med. 2011;364(25):2381-91. PMID 21639806.

At a median 35 months, invasive breast cancer occurred in 11 versus 32 women (annual incidence 0.19% versus 0.55%; HR 0.35, 95% CI 0.18 to 0.70). Adverse events occurred in 88% versus 85% (P = 0.003), with no significant differences in fractures, cardiovascular events, other cancers or treatment-related deaths.

Participants / model
4,560 postmenopausal women at moderately increased breast cancer risk
Treatment
Oral exemestane or placebo
Follow-up
Median follow-up 35 months
Study design
Randomized placebo-controlled trial (NCT00083174)
Funding
not stated in the source

Prevention is not a labeled US indication. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source

What has been measured in males given exemestane?

One short study in healthy males aged 14 to 26 is the main data set. In 12 subjects, 10 days of exemestane lowered estradiol by 32 to 38% and raised testosterone by 56 to 60%, with no change in lipids or IGF-I. It measured hormones only, not any clinical outcome.

In healthy eugonadal males aged 14 to 26, a randomized crossover of exemestane at 25 mg and 50 mg daily for 10 days (12 subjects) lowered plasma estradiol by 38% and 32% and raised testosterone by 60% and 56%. Lipids and IGF-I did not change.

In a single-dose pharmacokinetic study in 10 young males, concentrations peaked at 1 hour, the terminal half-life was 8.9 hours, and maximal estradiol suppression of 62% came at 12 hours. The label separately reports that single-dose PK in fasted healthy men (mean age 32) was similar to that in fasted healthy postmenopausal women.

These are short-term hormone measures with no clinical outcome. PubMed lists an erratum for the young-male paper; the numbers here are from the abstract.

Healthy males aged 14 to 26: estradiol down 32 to 38%, testosterone up 56 to 60%

Human study

Mauras N et al. J Clin Endocrinol Metab. 2003;88(12):5951-6. PMID 14671195.

In a randomized crossover of two daily doses for 10 days (12 subjects), exemestane at 25 mg and 50 mg lowered plasma estradiol by 38% and 32% and raised testosterone by 60% and 56%; lipids and IGF-I did not change. In a single-dose study (10 subjects), concentrations peaked at 1 hour, the terminal half-life was 8.9 hours, and maximal estradiol suppression of 62% came at 12 hours.

Participants / model
12 healthy eugonadal males aged 14 to 26 (crossover) and 10 healthy young males (PK study)
Treatment
Oral exemestane 25 or 50 mg daily for 10 days; a 25 mg dose in the PK study
Follow-up
10 days
Study design
Randomized crossover study and a separate PK study
Funding
not stated in the source

This is the main male data set: short-term hormone measures only, with no clinical outcome. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source
AROMASIN label, version effective 24 December 2025: indication, mechanism, PK, warnings

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

The label approves AROMASIN for postmenopausal women with estrogen-receptor-positive early breast cancer who switch to it after 2 to 3 years of tamoxifen to complete 5 years of adjuvant therapy, and for advanced breast cancer that progressed on tamoxifen. It calls exemestane an irreversible steroidal aromatase inactivator, similar in structure to androstenedione, that is processed to an intermediate binding the enzyme's active site (suicide inhibition). In postmenopausal women it suppressed circulating estrogens by at least 85% to 95% and whole-body aromatization by 98%; after one dose, maximal suppression came at 2 to 3 days and lasted 4 to 5 days. About 42% of a radiolabeled dose was absorbed, a high-fat breakfast raised AUC by 59% and Cmax by 39%, and the mean terminal half-life in healthy postmenopausal women is about 24 hours. Single-dose PK in fasted healthy men (mean age 32) was similar to that in fasted healthy postmenopausal women. Warnings cover bone loss (at 24 months lumbar spine bone mineral density fell 3.1% versus 0.2% on tamoxifen in IES, and 3.5% versus 2.4% on placebo in study 027), vitamin D assessment, avoiding systemic estrogen-containing agents, and embryo-fetal toxicity.

Participants / model
Postmenopausal women with breast cancer; healthy postmenopausal women and healthy men for PK
Treatment
AROMASIN oral tablets
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

The label's clinical data are in postmenopausal women. Its only male data are single-dose PK in healthy men.

Read the original source

Does exemestane have androgenic effects?

Receptor and cell work suggest its main metabolite can act through the androgen receptor, but no study found measured an androgenic effect in men. At the labeled dose in women, testosterone fell slightly, and it rose only at 200 mg a day or more.

The label reports slight androgen-receptor binding for exemestane (0.28% relative to DHT) and 100 times that affinity for its 17-dihydro metabolite, and says one metabolite may have androgenic activity. In its endocrine data, daily doses up to the labeled dose did not significantly change androstenedione, DHEA-S or 17-hydroxyprogesterone and were associated with small decreases in testosterone. Testosterone and androstenedione rose only at 200 mg a day or more. SHBG fell dose-dependently from 2.5 mg a day, LH and FSH rose slightly, and in postmenopausal women in study 027 HDL cholesterol fell 6 to 9% and homocysteine rose 18% versus 12% on placebo.

These are hormone and lipid measures, not androgenic clinical effects, and the label does not attribute any of them to men.

In MCF-7 and T47D breast cancer cells, the primary metabolite 17-hydroexemestane bound estrogen receptor alpha very weakly and the androgen receptor strongly, and acted through the androgen receptor at low nanomolar concentrations in T47D cells. The authors conclude it exerts biological effects as an androgen. This is receptor and cell-line evidence, not a measured effect in people.

AROMASIN label: slight androgen-receptor binding, hormone and lipid changes

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3. Endocrine and pharmacodynamic sections.

The label reports slight androgen-receptor binding for exemestane (0.28% relative to DHT) and 100 times that affinity for its 17-dihydro metabolite, and says one metabolite may have androgenic activity. In its endocrine data, daily doses up to the labeled dose did not significantly change androstenedione, DHEA-S or 17-hydroxyprogesterone and were associated with small decreases in testosterone; testosterone and androstenedione rose only at 200 mg a day or more. SHBG fell dose-dependently from 2.5 mg a day, LH and FSH rose slightly, and in postmenopausal women in study 027 HDL cholesterol fell 6 to 9% and homocysteine rose 18% versus 12% on placebo.

Participants / model
Label endocrine data (estrogen dose-finding was in postmenopausal women); study 027 in postmenopausal women
Treatment
AROMASIN oral tablets, daily doses from 2.5 mg to 200 mg or more in the endocrine data
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

These are hormone and lipid measures, not androgenic clinical effects, and the label does not attribute any of them to men.

Read the original source
Cell study: the main metabolite binds the androgen receptor strongly

Cell study

Ariazi EA et al. Mol Cancer Ther. 2007;6(11):2817-27. PMID 17989318.

In MCF-7 and T47D breast cancer cells, exemestane's primary metabolite 17-hydroexemestane bound estrogen receptor alpha very weakly and the androgen receptor strongly, and acted through the androgen receptor at low nanomolar concentrations in T47D cells. The authors conclude it exerts biological effects as an androgen.

Participants / model
Human breast cancer cell lines (MCF-7, T47D)
Treatment
17-hydroexemestane in vitro
Follow-up
Not applicable
Study design
In vitro mechanistic study
Funding
not stated in the source

This is receptor and cell-line evidence for the androgenic claim, not a measured effect in people.

Read the original source

Is exemestane better for estradiol control on a steroid cycle?

Only the estradiol-lowering part has been measured in males, as a short hormone change. A PubMed search on 9 October 2026 found no study in men or steroid users of exemestane for gynecomastia, estradiol control or androgenic effects.

Sellers describe exemestane, a steroidal aromatase inactivator, as favored for estradiol control on steroid cycles and as bringing androgenic side benefits. The estradiol-lowering part is measured in males only in the 10-day study above, as a hormone change with no clinical outcome.

A PubMed search on 9 October 2026 for exemestane with hypogonadism, infertility, gynecomastia, anabolic, bodybuilding, delayed puberty or short stature terms returned 18 records: six reviews (one on ovulation induction in PCOS), two animal studies, a pharmacovigilance database study, a crystal-engineering paper, four drug-detection method papers, a fungal biotransformation study, one pediatric case report (a boy with congenital adrenal hyperplasia), and the forum and seized-product analyses below. None tested exemestane in men or steroid users for gynecomastia, estradiol control or androgenic effects.

An analysis of 1,792 posts on a French bodybuilding forum (2013 to 2019), all by men with a mean age of 28.2 years, found aromatase inhibitors used mainly to counter aromatization of androgens, with a median exemestane course of 84 days at a mean 10 mg a day, obtained mainly online. This records how the drug is used, not whether it works.

Poland's official medicines control laboratory tested 63 seized illegal products sold for post-cycle therapy (2020 to 2024). 34.9% did not contain the declared active ingredient (20.6% contained no active ingredient and 14.3% a different one), and 6.4% contained an extra undeclared ingredient. Per-drug results are not given in the abstract, so a gray-market product may not be the drug tested in the studies on this page.

PubMed search, 9 October 2026: 18 records, none testing exemestane in men or steroid users

PubMed search record

PubMed search run on 9 October 2026: exemestane[tiab] AND (hypogonadism[tiab] OR hypogonadal[tiab] OR infertility[tiab] OR infertile[tiab] OR gynecomastia[tiab] OR gynaecomastia[tiab] OR anabolic[tiab] OR bodybuild*[tiab] OR delayed puberty[tiab] OR short stature[tiab]). 18 records returned.

The search returned 18 records: six reviews (one on ovulation induction in PCOS), two animal studies, a pharmacovigilance database study, a crystal-engineering paper, four drug-detection method papers, a fungal biotransformation study, one pediatric case report (a boy with congenital adrenal hyperplasia), and the forum and seized-product analyses described on this page. None tested exemestane in men or steroid users for gynecomastia, estradiol control or androgenic effects.

Participants / model
Records returned, not a population
Treatment
Not applicable
Follow-up
Search run on 9 October 2026
Study design
Literature search
Funding
not stated in the source

A search result shows what PubMed returned on that date. It is not proof that no unindexed study exists.

Read the original source
1,792 forum posts, 2013 to 2019: how aromatase inhibitors are used

Human study

Rochoy M et al. Therapie. 2022;77(6):683-691. PMID 35660259.

Aromatase inhibitors were used mainly to counter aromatization of androgens. The median exemestane course was 84 days at a mean 10 mg a day, obtained mainly online.

Participants / model
Men posting on one French bodybuilding forum, mean age 28.2 years
Treatment
Self-sourced oral exemestane, self-reported doses
Follow-up
Posts from 2013 to 2019
Study design
Observational analysis of 1,792 forum posts
Funding
not stated in the source

This records how the drug is used, not whether it works. Doses are self-reported.

Read the original source
63 seized products, 2020 to 2024: 34.9% lacked the declared ingredient

Regulatory record

Blazewicz A et al. Front Chem. 2025;13:1536858. PMID 40177353.

Of 63 seized products sold for post-cycle therapy and labeled as SERMs, aromatase inhibitors (anastrozole, letrozole, exemestane) or other agents, 34.9% did not contain the declared active ingredient (20.6% contained no active ingredient and 14.3% a different one), and 6.4% contained an extra undeclared ingredient. Per-drug results are not given in the abstract.

Participants / model
Seized products, not a clinical population (63 of 601 samples)
Treatment
Illegal post-cycle therapy products as seized
Follow-up
Products seized 2020 to 2024
Study design
Official laboratory product analysis
Funding
not stated in the source

A gray-market product may not be the drug tested in the studies on this page.

Read the original source

How does exemestane work, and what does the body do with it?

Exemestane is an irreversible steroidal aromatase inactivator. In postmenopausal women the label reports circulating estrogens suppressed by at least 85% to 95%, with a mean terminal half-life of about 24 hours. A separate study in young males found a terminal half-life of 8.9 hours.

The label calls exemestane an irreversible steroidal aromatase inactivator, similar in structure to androstenedione, that is processed to an intermediate binding the enzyme's active site (suicide inhibition). In postmenopausal women it suppressed circulating estrogens by at least 85% to 95% and whole-body aromatization by 98%. After one dose, maximal suppression came at 2 to 3 days and lasted 4 to 5 days.

About 42% of a radiolabeled dose was absorbed, and a high-fat breakfast raised AUC by 59% and Cmax by 39%. The mean terminal half-life in healthy postmenopausal women is about 24 hours.

In 10 young males in a separate single-dose study, concentrations peaked at 1 hour and the terminal half-life was 8.9 hours. The two half-lives come from different studies and methods and are not interchangeable.

AROMASIN label, version effective 24 December 2025: indication, mechanism, PK, warnings

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

The label approves AROMASIN for postmenopausal women with estrogen-receptor-positive early breast cancer who switch to it after 2 to 3 years of tamoxifen to complete 5 years of adjuvant therapy, and for advanced breast cancer that progressed on tamoxifen. It calls exemestane an irreversible steroidal aromatase inactivator, similar in structure to androstenedione, that is processed to an intermediate binding the enzyme's active site (suicide inhibition). In postmenopausal women it suppressed circulating estrogens by at least 85% to 95% and whole-body aromatization by 98%; after one dose, maximal suppression came at 2 to 3 days and lasted 4 to 5 days. About 42% of a radiolabeled dose was absorbed, a high-fat breakfast raised AUC by 59% and Cmax by 39%, and the mean terminal half-life in healthy postmenopausal women is about 24 hours. Single-dose PK in fasted healthy men (mean age 32) was similar to that in fasted healthy postmenopausal women. Warnings cover bone loss (at 24 months lumbar spine bone mineral density fell 3.1% versus 0.2% on tamoxifen in IES, and 3.5% versus 2.4% on placebo in study 027), vitamin D assessment, avoiding systemic estrogen-containing agents, and embryo-fetal toxicity.

Participants / model
Postmenopausal women with breast cancer; healthy postmenopausal women and healthy men for PK
Treatment
AROMASIN oral tablets
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

The label's clinical data are in postmenopausal women. Its only male data are single-dose PK in healthy men.

Read the original source
Healthy males aged 14 to 26: estradiol down 32 to 38%, testosterone up 56 to 60%

Human study

Mauras N et al. J Clin Endocrinol Metab. 2003;88(12):5951-6. PMID 14671195.

In a randomized crossover of two daily doses for 10 days (12 subjects), exemestane at 25 mg and 50 mg lowered plasma estradiol by 38% and 32% and raised testosterone by 60% and 56%; lipids and IGF-I did not change. In a single-dose study (10 subjects), concentrations peaked at 1 hour, the terminal half-life was 8.9 hours, and maximal estradiol suppression of 62% came at 12 hours.

Participants / model
12 healthy eugonadal males aged 14 to 26 (crossover) and 10 healthy young males (PK study)
Treatment
Oral exemestane 25 or 50 mg daily for 10 days; a 25 mg dose in the PK study
Follow-up
10 days
Study design
Randomized crossover study and a separate PK study
Funding
not stated in the source

This is the main male data set: short-term hormone measures only, with no clinical outcome. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source

Can exemestane distort hormone blood test results?

In 15 women taking exemestane, all four androstenedione immunoassays gave falsely high results that tracked serum exemestane, and one estradiol immunoassay read falsely high in 20% of patients. It was not tested in men.

In 15 women taking exemestane, all four androstenedione immunoassays tested gave falsely high results that tracked serum exemestane, confirmed in vitro as cross-reactivity with exemestane. One immunoassay gave falsely high estradiol in 20% of patients, which in-vitro tests did not attribute to exemestane or 17-hydroexemestane. Results were compared against LC-MS.

The study was in women and was not tested in men, so how much it applies to male hormone panels is not established.

15 women: androstenedione immunoassays falsely high on exemestane

Human study

Giralt M et al. Ann Lab Med. 2025;45(4):410-419. PMID 40114653.

In 15 women taking exemestane, all four androstenedione immunoassays tested gave falsely high results that tracked serum exemestane, confirmed in vitro as cross-reactivity with exemestane. One immunoassay gave falsely high estradiol in 20% of patients, which in-vitro tests did not attribute to exemestane or 17-hydroexemestane. Results were compared against LC-MS.

Participants / model
15 women on exemestane; spiked serum in vitro
Treatment
Oral exemestane taken by the women
Follow-up
Not stated in the abstract
Study design
Laboratory study comparing immunoassays with LC-MS
Funding
not stated in the source

Shown in women. It was not tested in men.

Read the original source

What risks do the label and the studies report?

The label warns of bone loss, advises assessing vitamin D and avoiding systemic estrogen-containing agents, and warns of embryo-fetal toxicity. HDL cholesterol fell 6 to 9% in postmenopausal women in study 027. These data come from women.

At 24 months, lumbar spine bone mineral density fell 3.1% versus 0.2% on tamoxifen in IES, and 3.5% versus 2.4% on placebo in study 027. The label advises assessing vitamin D, advises avoiding systemic estrogen-containing agents, and warns of embryo-fetal toxicity. In postmenopausal women in study 027, HDL cholesterol fell 6 to 9% and homocysteine rose 18% versus 12% on placebo.

In MAP.3, adverse events occurred in 88% versus 85% on placebo (P = 0.003), with no significant differences in fractures, cardiovascular events, other cancers or treatment-related deaths. In the 10-day study in 12 healthy young males, lipids and IGF-I did not change.

Product identity is a separate concern: 34.9% of 63 seized post-cycle therapy products did not contain the declared active ingredient.

AROMASIN label, version effective 24 December 2025: indication, mechanism, PK, warnings

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

The label approves AROMASIN for postmenopausal women with estrogen-receptor-positive early breast cancer who switch to it after 2 to 3 years of tamoxifen to complete 5 years of adjuvant therapy, and for advanced breast cancer that progressed on tamoxifen. It calls exemestane an irreversible steroidal aromatase inactivator, similar in structure to androstenedione, that is processed to an intermediate binding the enzyme's active site (suicide inhibition). In postmenopausal women it suppressed circulating estrogens by at least 85% to 95% and whole-body aromatization by 98%; after one dose, maximal suppression came at 2 to 3 days and lasted 4 to 5 days. About 42% of a radiolabeled dose was absorbed, a high-fat breakfast raised AUC by 59% and Cmax by 39%, and the mean terminal half-life in healthy postmenopausal women is about 24 hours. Single-dose PK in fasted healthy men (mean age 32) was similar to that in fasted healthy postmenopausal women. Warnings cover bone loss (at 24 months lumbar spine bone mineral density fell 3.1% versus 0.2% on tamoxifen in IES, and 3.5% versus 2.4% on placebo in study 027), vitamin D assessment, avoiding systemic estrogen-containing agents, and embryo-fetal toxicity.

Participants / model
Postmenopausal women with breast cancer; healthy postmenopausal women and healthy men for PK
Treatment
AROMASIN oral tablets
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

The label's clinical data are in postmenopausal women. Its only male data are single-dose PK in healthy men.

Read the original source
AROMASIN label: slight androgen-receptor binding, hormone and lipid changes

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3. Endocrine and pharmacodynamic sections.

The label reports slight androgen-receptor binding for exemestane (0.28% relative to DHT) and 100 times that affinity for its 17-dihydro metabolite, and says one metabolite may have androgenic activity. In its endocrine data, daily doses up to the labeled dose did not significantly change androstenedione, DHEA-S or 17-hydroxyprogesterone and were associated with small decreases in testosterone; testosterone and androstenedione rose only at 200 mg a day or more. SHBG fell dose-dependently from 2.5 mg a day, LH and FSH rose slightly, and in postmenopausal women in study 027 HDL cholesterol fell 6 to 9% and homocysteine rose 18% versus 12% on placebo.

Participants / model
Label endocrine data (estrogen dose-finding was in postmenopausal women); study 027 in postmenopausal women
Treatment
AROMASIN oral tablets, daily doses from 2.5 mg to 200 mg or more in the endocrine data
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

These are hormone and lipid measures, not androgenic clinical effects, and the label does not attribute any of them to men.

Read the original source
MAP.3: 4,560 women, invasive breast cancer 11 versus 32

Randomized controlled trial

Goss PE et al. N Engl J Med. 2011;364(25):2381-91. PMID 21639806.

At a median 35 months, invasive breast cancer occurred in 11 versus 32 women (annual incidence 0.19% versus 0.55%; HR 0.35, 95% CI 0.18 to 0.70). Adverse events occurred in 88% versus 85% (P = 0.003), with no significant differences in fractures, cardiovascular events, other cancers or treatment-related deaths.

Participants / model
4,560 postmenopausal women at moderately increased breast cancer risk
Treatment
Oral exemestane or placebo
Follow-up
Median follow-up 35 months
Study design
Randomized placebo-controlled trial (NCT00083174)
Funding
not stated in the source

Prevention is not a labeled US indication. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source
Healthy males aged 14 to 26: estradiol down 32 to 38%, testosterone up 56 to 60%

Human study

Mauras N et al. J Clin Endocrinol Metab. 2003;88(12):5951-6. PMID 14671195.

In a randomized crossover of two daily doses for 10 days (12 subjects), exemestane at 25 mg and 50 mg lowered plasma estradiol by 38% and 32% and raised testosterone by 60% and 56%; lipids and IGF-I did not change. In a single-dose study (10 subjects), concentrations peaked at 1 hour, the terminal half-life was 8.9 hours, and maximal estradiol suppression of 62% came at 12 hours.

Participants / model
12 healthy eugonadal males aged 14 to 26 (crossover) and 10 healthy young males (PK study)
Treatment
Oral exemestane 25 or 50 mg daily for 10 days; a 25 mg dose in the PK study
Follow-up
10 days
Study design
Randomized crossover study and a separate PK study
Funding
not stated in the source

This is the main male data set: short-term hormone measures only, with no clinical outcome. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source
63 seized products, 2020 to 2024: 34.9% lacked the declared ingredient

Regulatory record

Blazewicz A et al. Front Chem. 2025;13:1536858. PMID 40177353.

Of 63 seized products sold for post-cycle therapy and labeled as SERMs, aromatase inhibitors (anastrozole, letrozole, exemestane) or other agents, 34.9% did not contain the declared active ingredient (20.6% contained no active ingredient and 14.3% a different one), and 6.4% contained an extra undeclared ingredient. Per-drug results are not given in the abstract.

Participants / model
Seized products, not a clinical population (63 of 601 samples)
Treatment
Illegal post-cycle therapy products as seized
Follow-up
Products seized 2020 to 2024
Study design
Official laboratory product analysis
Funding
not stated in the source

A gray-market product may not be the drug tested in the studies on this page.

Read the original source

Why does exemestane sit in A tier?

The A rests on an FDA approval since 1999 and two large breast cancer trials in women. In males the record is one 10-day hormone study, and the androgenic claim rests on receptor binding and cell work.

The A applies to the breast cancer use in postmenopausal women, backed by the 4,724-woman IES trial and the 4,560-woman MAP.3 prevention trial. The supplier's use in men is off-label and rests on one 10-day study in 12 healthy young males plus a single-dose PK comparison in the label.

Only the estradiol-lowering part has been measured in males, as a hormone change of 32 to 38% with testosterone up 56 to 60%. The androgenic claim rests on receptor binding and breast cancer cell work on a metabolite, while at the labeled dose in women testosterone fell slightly. A PubMed search on 9 October 2026 found no study in men or steroid users of gynecomastia, estradiol control or androgenic effects.

AROMASIN label, version effective 24 December 2025: indication, mechanism, PK, warnings

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

The label approves AROMASIN for postmenopausal women with estrogen-receptor-positive early breast cancer who switch to it after 2 to 3 years of tamoxifen to complete 5 years of adjuvant therapy, and for advanced breast cancer that progressed on tamoxifen. It calls exemestane an irreversible steroidal aromatase inactivator, similar in structure to androstenedione, that is processed to an intermediate binding the enzyme's active site (suicide inhibition). In postmenopausal women it suppressed circulating estrogens by at least 85% to 95% and whole-body aromatization by 98%; after one dose, maximal suppression came at 2 to 3 days and lasted 4 to 5 days. About 42% of a radiolabeled dose was absorbed, a high-fat breakfast raised AUC by 59% and Cmax by 39%, and the mean terminal half-life in healthy postmenopausal women is about 24 hours. Single-dose PK in fasted healthy men (mean age 32) was similar to that in fasted healthy postmenopausal women. Warnings cover bone loss (at 24 months lumbar spine bone mineral density fell 3.1% versus 0.2% on tamoxifen in IES, and 3.5% versus 2.4% on placebo in study 027), vitamin D assessment, avoiding systemic estrogen-containing agents, and embryo-fetal toxicity.

Participants / model
Postmenopausal women with breast cancer; healthy postmenopausal women and healthy men for PK
Treatment
AROMASIN oral tablets
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

The label's clinical data are in postmenopausal women. Its only male data are single-dose PK in healthy men.

Read the original source
IES: 4,724 postmenopausal women, switch to exemestane after tamoxifen

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) prescribing information, label version effective 24 December 2025, section 14.1 (Intergroup Exemestane Study). Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

IES randomized 4,724 postmenopausal women who were disease-free after 2 to 3 years of adjuvant tamoxifen to switch to exemestane or continue tamoxifen, completing 5 years in total. Disease-free survival improved with the switch (HR 0.69, 95% CI 0.58 to 0.82; hormone receptor-positive subgroup HR 0.65, 0.53 to 0.79). At a median 119 months, overall survival did not differ significantly (467 deaths, 19.9%, versus 510, 21.5%).

Participants / model
4,724 postmenopausal women with early breast cancer
Treatment
Oral exemestane 25 mg daily versus continued tamoxifen 20 or 30 mg daily
Follow-up
5 years of total adjuvant therapy; median follow-up 119 months for overall survival
Study design
Phase 3 randomized trial, results read from label section 14.1
Funding
not stated in the source

Women only. The result does not apply to men or to steroid-cycle use.

Read the original source
MAP.3: 4,560 women, invasive breast cancer 11 versus 32

Randomized controlled trial

Goss PE et al. N Engl J Med. 2011;364(25):2381-91. PMID 21639806.

At a median 35 months, invasive breast cancer occurred in 11 versus 32 women (annual incidence 0.19% versus 0.55%; HR 0.35, 95% CI 0.18 to 0.70). Adverse events occurred in 88% versus 85% (P = 0.003), with no significant differences in fractures, cardiovascular events, other cancers or treatment-related deaths.

Participants / model
4,560 postmenopausal women at moderately increased breast cancer risk
Treatment
Oral exemestane or placebo
Follow-up
Median follow-up 35 months
Study design
Randomized placebo-controlled trial (NCT00083174)
Funding
not stated in the source

Prevention is not a labeled US indication. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source
Healthy males aged 14 to 26: estradiol down 32 to 38%, testosterone up 56 to 60%

Human study

Mauras N et al. J Clin Endocrinol Metab. 2003;88(12):5951-6. PMID 14671195.

In a randomized crossover of two daily doses for 10 days (12 subjects), exemestane at 25 mg and 50 mg lowered plasma estradiol by 38% and 32% and raised testosterone by 60% and 56%; lipids and IGF-I did not change. In a single-dose study (10 subjects), concentrations peaked at 1 hour, the terminal half-life was 8.9 hours, and maximal estradiol suppression of 62% came at 12 hours.

Participants / model
12 healthy eugonadal males aged 14 to 26 (crossover) and 10 healthy young males (PK study)
Treatment
Oral exemestane 25 or 50 mg daily for 10 days; a 25 mg dose in the PK study
Follow-up
10 days
Study design
Randomized crossover study and a separate PK study
Funding
not stated in the source

This is the main male data set: short-term hormone measures only, with no clinical outcome. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source
Cell study: the main metabolite binds the androgen receptor strongly

Cell study

Ariazi EA et al. Mol Cancer Ther. 2007;6(11):2817-27. PMID 17989318.

In MCF-7 and T47D breast cancer cells, exemestane's primary metabolite 17-hydroexemestane bound estrogen receptor alpha very weakly and the androgen receptor strongly, and acted through the androgen receptor at low nanomolar concentrations in T47D cells. The authors conclude it exerts biological effects as an androgen.

Participants / model
Human breast cancer cell lines (MCF-7, T47D)
Treatment
17-hydroexemestane in vitro
Follow-up
Not applicable
Study design
In vitro mechanistic study
Funding
not stated in the source

This is receptor and cell-line evidence for the androgenic claim, not a measured effect in people.

Read the original source
PubMed search, 9 October 2026: 18 records, none testing exemestane in men or steroid users

PubMed search record

PubMed search run on 9 October 2026: exemestane[tiab] AND (hypogonadism[tiab] OR hypogonadal[tiab] OR infertility[tiab] OR infertile[tiab] OR gynecomastia[tiab] OR gynaecomastia[tiab] OR anabolic[tiab] OR bodybuild*[tiab] OR delayed puberty[tiab] OR short stature[tiab]). 18 records returned.

The search returned 18 records: six reviews (one on ovulation induction in PCOS), two animal studies, a pharmacovigilance database study, a crystal-engineering paper, four drug-detection method papers, a fungal biotransformation study, one pediatric case report (a boy with congenital adrenal hyperplasia), and the forum and seized-product analyses described on this page. None tested exemestane in men or steroid users for gynecomastia, estradiol control or androgenic effects.

Participants / model
Records returned, not a population
Treatment
Not applicable
Follow-up
Search run on 9 October 2026
Study design
Literature search
Funding
not stated in the source

A search result shows what PubMed returned on that date. It is not proof that no unindexed study exists.

Read the original source

Studies and sources

AROMASIN label, version effective 24 December 2025: indication, mechanism, PK, warnings

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

The label approves AROMASIN for postmenopausal women with estrogen-receptor-positive early breast cancer who switch to it after 2 to 3 years of tamoxifen to complete 5 years of adjuvant therapy, and for advanced breast cancer that progressed on tamoxifen. It calls exemestane an irreversible steroidal aromatase inactivator, similar in structure to androstenedione, that is processed to an intermediate binding the enzyme's active site (suicide inhibition). In postmenopausal women it suppressed circulating estrogens by at least 85% to 95% and whole-body aromatization by 98%; after one dose, maximal suppression came at 2 to 3 days and lasted 4 to 5 days. About 42% of a radiolabeled dose was absorbed, a high-fat breakfast raised AUC by 59% and Cmax by 39%, and the mean terminal half-life in healthy postmenopausal women is about 24 hours. Single-dose PK in fasted healthy men (mean age 32) was similar to that in fasted healthy postmenopausal women. Warnings cover bone loss (at 24 months lumbar spine bone mineral density fell 3.1% versus 0.2% on tamoxifen in IES, and 3.5% versus 2.4% on placebo in study 027), vitamin D assessment, avoiding systemic estrogen-containing agents, and embryo-fetal toxicity.

Participants / model
Postmenopausal women with breast cancer; healthy postmenopausal women and healthy men for PK
Treatment
AROMASIN oral tablets
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

The label's clinical data are in postmenopausal women. Its only male data are single-dose PK in healthy men.

Read the original source
AROMASIN label: slight androgen-receptor binding, hormone and lipid changes

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) oral tablets, prescribing information, label version effective 24 December 2025. Set ID cf066b7a-032a-416c-8d40-15ba581423e3. Endocrine and pharmacodynamic sections.

The label reports slight androgen-receptor binding for exemestane (0.28% relative to DHT) and 100 times that affinity for its 17-dihydro metabolite, and says one metabolite may have androgenic activity. In its endocrine data, daily doses up to the labeled dose did not significantly change androstenedione, DHEA-S or 17-hydroxyprogesterone and were associated with small decreases in testosterone; testosterone and androstenedione rose only at 200 mg a day or more. SHBG fell dose-dependently from 2.5 mg a day, LH and FSH rose slightly, and in postmenopausal women in study 027 HDL cholesterol fell 6 to 9% and homocysteine rose 18% versus 12% on placebo.

Participants / model
Label endocrine data (estrogen dose-finding was in postmenopausal women); study 027 in postmenopausal women
Treatment
AROMASIN oral tablets, daily doses from 2.5 mg to 200 mg or more in the endocrine data
Follow-up
Label version effective 24 December 2025
Study design
FDA prescribing information
Funding
not stated in the source

These are hormone and lipid measures, not androgenic clinical effects, and the label does not attribute any of them to men.

Read the original source
IES: 4,724 postmenopausal women, switch to exemestane after tamoxifen

FDA prescribing information

DailyMed, U.S. National Library of Medicine. AROMASIN (exemestane) prescribing information, label version effective 24 December 2025, section 14.1 (Intergroup Exemestane Study). Set ID cf066b7a-032a-416c-8d40-15ba581423e3.

IES randomized 4,724 postmenopausal women who were disease-free after 2 to 3 years of adjuvant tamoxifen to switch to exemestane or continue tamoxifen, completing 5 years in total. Disease-free survival improved with the switch (HR 0.69, 95% CI 0.58 to 0.82; hormone receptor-positive subgroup HR 0.65, 0.53 to 0.79). At a median 119 months, overall survival did not differ significantly (467 deaths, 19.9%, versus 510, 21.5%).

Participants / model
4,724 postmenopausal women with early breast cancer
Treatment
Oral exemestane 25 mg daily versus continued tamoxifen 20 or 30 mg daily
Follow-up
5 years of total adjuvant therapy; median follow-up 119 months for overall survival
Study design
Phase 3 randomized trial, results read from label section 14.1
Funding
not stated in the source

Women only. The result does not apply to men or to steroid-cycle use.

Read the original source
Drugs@FDA: AROMASIN approved 21 October 1999

Regulatory record

U.S. Food and Drug Administration. Drugs@FDA application record for NDA 020753 (AROMASIN). Date read from the openFDA Drugs@FDA record.

FDA approved AROMASIN under NDA 020753 on 21 October 1999 (Pfizer).

Participants / model
Not a clinical population
Treatment
Drug application
Follow-up
Approved 1999
Study design
FDA application record
Funding
not stated in the source

This record gives the approval date and applicant. Indications come from the product label.

Read the original source
MAP.3: 4,560 women, invasive breast cancer 11 versus 32

Randomized controlled trial

Goss PE et al. N Engl J Med. 2011;364(25):2381-91. PMID 21639806.

At a median 35 months, invasive breast cancer occurred in 11 versus 32 women (annual incidence 0.19% versus 0.55%; HR 0.35, 95% CI 0.18 to 0.70). Adverse events occurred in 88% versus 85% (P = 0.003), with no significant differences in fractures, cardiovascular events, other cancers or treatment-related deaths.

Participants / model
4,560 postmenopausal women at moderately increased breast cancer risk
Treatment
Oral exemestane or placebo
Follow-up
Median follow-up 35 months
Study design
Randomized placebo-controlled trial (NCT00083174)
Funding
not stated in the source

Prevention is not a labeled US indication. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source
Healthy males aged 14 to 26: estradiol down 32 to 38%, testosterone up 56 to 60%

Human study

Mauras N et al. J Clin Endocrinol Metab. 2003;88(12):5951-6. PMID 14671195.

In a randomized crossover of two daily doses for 10 days (12 subjects), exemestane at 25 mg and 50 mg lowered plasma estradiol by 38% and 32% and raised testosterone by 60% and 56%; lipids and IGF-I did not change. In a single-dose study (10 subjects), concentrations peaked at 1 hour, the terminal half-life was 8.9 hours, and maximal estradiol suppression of 62% came at 12 hours.

Participants / model
12 healthy eugonadal males aged 14 to 26 (crossover) and 10 healthy young males (PK study)
Treatment
Oral exemestane 25 or 50 mg daily for 10 days; a 25 mg dose in the PK study
Follow-up
10 days
Study design
Randomized crossover study and a separate PK study
Funding
not stated in the source

This is the main male data set: short-term hormone measures only, with no clinical outcome. PubMed lists an erratum for this paper; the numbers here are from the abstract.

Read the original source
Cell study: the main metabolite binds the androgen receptor strongly

Cell study

Ariazi EA et al. Mol Cancer Ther. 2007;6(11):2817-27. PMID 17989318.

In MCF-7 and T47D breast cancer cells, exemestane's primary metabolite 17-hydroexemestane bound estrogen receptor alpha very weakly and the androgen receptor strongly, and acted through the androgen receptor at low nanomolar concentrations in T47D cells. The authors conclude it exerts biological effects as an androgen.

Participants / model
Human breast cancer cell lines (MCF-7, T47D)
Treatment
17-hydroexemestane in vitro
Follow-up
Not applicable
Study design
In vitro mechanistic study
Funding
not stated in the source

This is receptor and cell-line evidence for the androgenic claim, not a measured effect in people.

Read the original source
15 women: androstenedione immunoassays falsely high on exemestane

Human study

Giralt M et al. Ann Lab Med. 2025;45(4):410-419. PMID 40114653.

In 15 women taking exemestane, all four androstenedione immunoassays tested gave falsely high results that tracked serum exemestane, confirmed in vitro as cross-reactivity with exemestane. One immunoassay gave falsely high estradiol in 20% of patients, which in-vitro tests did not attribute to exemestane or 17-hydroexemestane. Results were compared against LC-MS.

Participants / model
15 women on exemestane; spiked serum in vitro
Treatment
Oral exemestane taken by the women
Follow-up
Not stated in the abstract
Study design
Laboratory study comparing immunoassays with LC-MS
Funding
not stated in the source

Shown in women. It was not tested in men.

Read the original source
1,792 forum posts, 2013 to 2019: how aromatase inhibitors are used

Human study

Rochoy M et al. Therapie. 2022;77(6):683-691. PMID 35660259.

Aromatase inhibitors were used mainly to counter aromatization of androgens. The median exemestane course was 84 days at a mean 10 mg a day, obtained mainly online.

Participants / model
Men posting on one French bodybuilding forum, mean age 28.2 years
Treatment
Self-sourced oral exemestane, self-reported doses
Follow-up
Posts from 2013 to 2019
Study design
Observational analysis of 1,792 forum posts
Funding
not stated in the source

This records how the drug is used, not whether it works. Doses are self-reported.

Read the original source
63 seized products, 2020 to 2024: 34.9% lacked the declared ingredient

Regulatory record

Blazewicz A et al. Front Chem. 2025;13:1536858. PMID 40177353.

Of 63 seized products sold for post-cycle therapy and labeled as SERMs, aromatase inhibitors (anastrozole, letrozole, exemestane) or other agents, 34.9% did not contain the declared active ingredient (20.6% contained no active ingredient and 14.3% a different one), and 6.4% contained an extra undeclared ingredient. Per-drug results are not given in the abstract.

Participants / model
Seized products, not a clinical population (63 of 601 samples)
Treatment
Illegal post-cycle therapy products as seized
Follow-up
Products seized 2020 to 2024
Study design
Official laboratory product analysis
Funding
not stated in the source

A gray-market product may not be the drug tested in the studies on this page.

Read the original source
PubChem: exemestane identity

Chemical identity record

National Library of Medicine. PubChem compound record CID 60198 (exemestane).

Exemestane: PubChem CID 60198, C20H24O2, 296.4 g/mol, CAS 107868-30-4, also named 6-methyleneandrosta-1,4-diene-3,17-dione. Label tablets contain exemestane itself, not a salt.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined molecule
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only; it says nothing about efficacy or safety.

Read the original source

Why is Exemestane in A tier?

A fits an approved drug promoted for an off-label use. Exemestane has been FDA-approved since 1999 and has two large breast cancer trials, but that grade belongs to the use in postmenopausal women. In males the record is one 10-day hormone study, and the searches run on 9 October 2026 found no study of gynecomastia, estradiol control or androgenic effects.