Generic Name: Exemestane
Brand Names: Aromasin
Exemestane is a steroidal aromatase inhibitor for hormone receptor-positive breast cancer.
Aromatase Inhibitor (Steroidal, Irreversible)
Contraindicated in pregnancy. May cause fetal harm. Not indicated for premenopausal women. Women of reproductive potential should verify negative pregnancy status and use effective contraception.
Oral tablet 25 mg
These are general dosage guidelines. Your doctor will determine the appropriate dose for your specific situation.
Exemestane is a steroidal aromatase inhibitor used in the treatment of hormone receptor-positive breast cancer in postmenopausal women. This medication irreversibly inactivates aromatase, reducing estrogen production and thereby slowing the growth of estrogen-dependent tumors.
Exemestane is a steroidal compound structurally related to the natural substrate androstenedione. It acts as a false substrate for the aromatase enzyme complex, binding irreversibly to the enzyme's active site and causing permanent inactivation (suicide inhibition). Unlike non-steroidal aromatase inhibitors (letrozole, anastrozole), which reversibly bind to the enzyme, exemestane's irreversible binding means new enzyme synthesis is required to restore aromatase activity. This results in significant suppression (85-95%) of circulating estrogen levels in postmenopausal women, where aromatization of adrenal androgens is the primary estrogen source. Reduced estrogen levels slow the growth of estrogen receptor-positive breast cancer cells.
Exemestane is available as oral tablets containing 25 mg. The tablets should be taken once daily after a meal, as food increases absorption by approximately 40%. Generic formulations are available.
Exemestane is FDA-approved for adjuvant treatment of postmenopausal women with estrogen receptor-positive early breast cancer who have received 2-3 years of tamoxifen and are switched to exemestane to complete a total of 5 consecutive years of adjuvant hormonal therapy, and for treatment of advanced breast cancer in postmenopausal women whose disease has progressed following tamoxifen therapy. Clinical trials have demonstrated reduced recurrence rates and improved disease-free survival compared to continued tamoxifen.
The recommended dose is 25 mg once daily after a meal. Treatment should continue until tumor progression (in advanced disease) or for a total of 5 years of adjuvant hormonal therapy (in early breast cancer). For women also receiving strong CYP3A4 inducers, the dose may be increased to 50 mg once daily. No dose titration is required.
Exemestane can cause a decrease in bone mineral density; baseline and periodic bone mineral density assessments should be performed. Patients should receive vitamin D and calcium supplementation. The medication should not be used in premenopausal women—premenopausal status should be verified before starting therapy. Elevated liver enzymes, including hepatitis, have been reported. The medication may cause fetal harm; pregnancy should be ruled out before starting therapy.
Strong CYP3A4 inducers (rifampin, phenytoin, carbamazepine, St. John's Wort) reduce exemestane exposure; dose increase to 50 mg daily may be considered. Estrogen-containing products should not be used as they may interfere with exemestane's action. No significant interactions with CYP3A4 inhibitors have been observed. Exemestane does not significantly inhibit CYP enzymes at therapeutic concentrations.
Exemestane is contraindicated in premenopausal women and may cause fetal harm. Women of reproductive potential should use effective contraception during treatment and for 1 month after discontinuation. It is unknown whether exemestane is excreted in human breast milk; breastfeeding is not recommended. Safety and efficacy have not been established in pediatric patients. Elderly patients do not require dose adjustment. No dose adjustment is needed for renal impairment. Use with caution in patients with hepatic impairment, though no dose adjustment is recommended based on available data.
Exemestane is a steroidal aromatase inactivator that irreversibly binds to and permanently disables the aromatase enzyme. Letrozole and anastrozole are nonsteroidal inhibitors that reversibly bind to aromatase. Practically, all three are similarly effective, but exemestane may be tried when a patient has not responded to or cannot tolerate a nonsteroidal option.
Taking exemestane with food increases its absorption by approximately 40 percent compared to fasting. A high-fat meal provides the greatest increase in absorption. Taking it consistently after a meal ensures reliable blood levels.
Common side effects include hot flashes, fatigue, joint pain (arthralgia), headache, increased sweating, and insomnia. Musculoskeletal pain affects a significant proportion of patients. Regular exercise and maintaining a healthy weight may help reduce joint symptoms.
Yes. Exemestane significantly lowers estrogen, which leads to accelerated bone loss. Baseline and periodic DEXA scans are recommended. Your doctor may prescribe calcium, vitamin D, and bisphosphonates or denosumab if bone density becomes low.
Consider discussing these topics at your next appointment:
Medical Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with your healthcare provider before starting, stopping, or changing any medication. Your doctor can provide personalized recommendations based on your specific health condition and medical history.
