Exemestane
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Clinical data | |
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Pronunciation | /ˌɛksəˈmɛˌsteɪn/ EK-sə-ME-stayn |
Trade names | Aromasin |
Other names | FCE-24304 |
AHFS/Drugs.com | Monograph |
MedlinePlus | a607006 |
Routes of administration | By mouth |
Drug class | Aromatase inhibitor; Antiestrogen |
ATC code | |
Legal status | |
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Pharmacokinetic data | |
Bioavailability | ~60%[citation needed] |
Protein binding | 90% |
Metabolism | Liver (CYP3A4, aldo-keto reductase) |
Elimination half-life | 24 hours |
Duration of action | 4–5 days[citation needed] |
Excretion | Urine and feces ~ 1:1 (mainly metabolites) |
Identifiers | |
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JSmol) | |
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Exemestane, sold under the brand name Aromasin among others, is a medication used to treat breast cancer. It is a member of the class of antiestrogens known as aromatase inhibitors. Some breast cancers require estrogen to grow. Those cancers have estrogen receptors (ERs), and are called ER-positive. They may also be called estrogen-responsive, hormonally-responsive, or hormone-receptor-positive. Aromatase is an enzyme that synthesizes estrogen. Aromatase inhibitors block the synthesis of estrogen. This lowers the estrogen level, and slows the growth of cancers.
Medical uses
Exemestane is
Exemestane is also indicated for the treatment of advanced breast cancer in postmenopausal women whose disease has progressed following tamoxifen therapy.[5]
For premenopausal women with hormone-receptor–positive breast cancer, adjuvant treatment with ovarian suppression plus the aromatase inhibitor exemestane, as compared with ovarian suppression plus tamoxifen, provides a new treatment option that reduces the risk of recurrence. The TEXT and SOFT trials demonstrated improved disease free survival in patients treated with exemestane and ovarian suppression compared to the tamoxifen and ovarian suppression group. Premenopausal women who receive ovarian suppression may now benefit from an aromatase inhibitor, a class of drugs that until now has been recommended only for postmenopausal women.[6]
Contraindications
The drug is contraindicated in
Side effects
The most common side effects (more than 10% of patients) are
An occasional decrease in lymphocytes has been observed in approximately 20% of patients receiving Aromasin, particularly in patients with pre-existing lymphopenia.[9]
Exemestane has androgenic properties similarly to formestane and can produce androgenic side effects such as acne and weight gain, although these are generally associated with supratherapeutic dosages of the drug.[10]
Overdose
Single doses of up to at least 32-fold (800 mg), as well as continuous therapy with 24-fold (600 mg) the usual daily dose are well tolerated. No life-threatening overdosing is known in humans, but only in animal studies with 2000- to 4000-fold doses (adjusted to body surface area).[7]
Interactions
Exemestane is metabolized by the liver enzyme
Estrogens probably reduce exemestane effectiveness:[8] It would usually be counter-productive to reduce the body's estrogen synthesis with exemestane and then substitute estrogen with pharmaceuticals.
Pharmacology
Pharmacodynamics
Exemestane is an oral steroidal aromatase inhibitor that is used in ER-positive breast cancer in addition to surgery and/or radiation in post-menopausal women.
The main source of estrogen is the ovaries in premenopausal women, while in post-menopausal women most of the body's estrogen is produced via the conversion of androgens into estrogen by the aromatase enzyme in the peripheral tissues (i.e. adipose tissue like that of the breast) and a number of sites in the brain. Estrogen is produced locally via the actions of the aromatase enzyme in these peripheral tissues where it acts locally. Any circulating estrogen in post-menopausal women as well as men is the result of estrogen escaping local metabolism and entering the circulatory system.[12]
Exemestane is an irreversible, steroidal aromatase inactivator of type I, structurally related to the natural substrate
Type II aromatase inhibitors such as anastrozole and letrozole, by contrast, are not steroids and work by interfering with the aromatase's heme.[11]
A study conducted on young adult males found that the estrogen suppression rate for exemestane varied from 35% for estradiol (E2) to 70% for estrone (E1).[13]
Generation | Medication | Dosage | % inhibitiona | Classb | IC50c |
---|---|---|---|---|---|
First | Testolactone | 250 mg 4x/day p.o. | ? | Type I | ? |
100 mg 3x/week i.m. | ? | ||||
Rogletimide | 200 mg 2x/day p.o. 400 mg 2x/day p.o. 800 mg 2x/day p.o. |
50.6% 63.5% 73.8% |
Type II | ? | |
Aminoglutethimide | 250 mg mg 4x/day p.o. | 90.6% | Type II | 4,500 nM | |
Second | Formestane | 125 mg 1x/day p.o. 125 mg 2x/day p.o. 250 mg 1x/day p.o. |
72.3% 70.0% 57.3% |
Type I | 30 nM |
250 mg 1x/2 weeks i.m. 500 mg 1x/2 weeks i.m. 500 mg 1x/1 week i.m. |
84.8% 91.9% 92.5% | ||||
Fadrozole | 1 mg 1x/day p.o. 2 mg 2x/day p.o. |
82.4% 92.6% |
Type II | ? | |
Third | Exemestane | 25 mg 1x/day p.o. | 97.9% | Type I | 15 nM |
Anastrozole | 1 mg 1x/day p.o. 10 mg 1x/day p.o. |
96.7–97.3% 98.1% |
Type II | 10 nM | |
Letrozole | 0.5 mg 1x/day p.o. 2.5 mg 1x/day p.o. |
98.4% 98.9%–>99.1% |
Type II | 2.5 nM | |
Footnotes: a = In homogenates . Sources: See template.
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Pharmacokinetics
Exemestane is quickly absorbed from the gut, but undergoes a strong
Chemistry
Exemestane is known chemically as 6-methylideneandrosta-1,4-diene-3,17-dione. Like the aromatase inhibitors formestane and atamestane, exemestane is a steroid that is structurally similar to 4-androstenedione, the natural substrate of aromatase. It is distinguished from the natural substance only by the methylidene group in position 6 and an additional double bond in position 1.[15]
Pure exemestane is a white to off-white powder that is soluble in DMSO to at least 20 mg/mL. Optical rotation [α]D is +250 to 300° (per g/100 cm3 and decimetre at 589 nm wavelength).[16]
Society and culture
Performance enhancement
Exemestane has been used in
Along with other aromatase inhibitors, exemestane is on the World Anti-Doping Agency's list of prohibited substances.[18]
Research
Oral exemestane 25 mg/day for 2–3 years of adjuvant therapy was generally more effective than 5 years of continuous adjuvant tamoxifen in the treatment of postmenopausal women with early-stage estrogen receptor-positive/unknown receptor status breast in a large well-designed[citation needed] trial. Preliminary data from the open-label TEAM trial comparing exemestane with tamoxifen indicated in 2009 that exemestane 25 mg/day is also effective in the primary adjuvant treatment of early-stage breast cancer in postmenopausal women.[19]
Interim phase III trial results in 2011 showed that adding everolimus to exemestane therapy against advanced breast cancer can significantly improve progression-free survival compared with exemestane therapy alone.[20][21]
A Phase III trial was reported in 2011, concluding that the use of exemestane in postmenopausal women at an increased risk for breast cancer reduced the incidence of invasive breast cancer. In 4,560 women, after 35 months, the administration of exemestane at a dose of 25 mg/day resulted in a 65% reduction in the risk of breast cancer compared with placebo; annual incidence rates were 0.19% and 0.55%, respectively (hazard ratio: 0.35; 95% CI [0.18-0.70]; p = 0.002).[22]
References
- ^ "Aromasin - Summary of Product Characteristics (SmPC)". (emc). 16 May 2022. Retrieved 29 November 2022.
- ^ "Exemestane". ChEBI.
- S2CID 38977099.
- ^ "Exemestane Approval Letter" (PDF). U.S. Food and Drug Administration. 21 October 1999.
- ^ "Aromasin For Advanced Breast Cancer". Aromasin.com. Archived from the original on 28 March 2012.
- PMID 24881463.
- ^ ISBN 978-3-85200-181-4.
- ^ a b c Drugs.com: Monograph on exemestane.
- ^ "Aromasin - Summary of Product Characteristics (SMPC) - (Emc)".
- S2CID 34798824.
- ^ ISBN 978-3-7741-9846-3.
- S2CID 11210435.
- ^
Mauras N, Lima J, Patel D, Rini A, di Salle E, Kwok A, Lippe B (December 2003). "Pharmacokinetics and dose finding of a potent aromatase inhibitor, aromasin (exemestane), in young males". The Journal of Clinical Endocrinology and Metabolism. 88 (12): 5951–6. PMID 14671195.
- ISBN 3-8047-1763-2.
- ISBN 3-7692-3483-9.
- ^ Sigma-Aldrich Co., Exemestane, ≥ 98% (HPLC).
- ISBN 978-3-00-020944-4.
- ^ "Substance Classification Booklet, Version 4.0" (PDF). Canadian Centre for Ethics in Sport. January 2009. Archived from the original (PDF) on 27 September 2013.
- S2CID 249879736. Archived from the originalon 8 October 2011. Retrieved 29 March 2010.
- ^ "Positive Trial Data Leads Novartis to Plan Breast Cancer Filing for Afinitor by Year End". 2011.
- ^ "Exemestane 25 mg". www.melanotanexpress.com.
- ^ Goss PE (6 June 2011). "Exemestane Offers New Option for Breast Cancer Prevention". American Society of Clinical Oncology. Archived from the original on 11 July 2011. Retrieved 6 June 2011.