AROMASIN

What it is

Exemestane is available as white to off-white, circular, biconvex sugar-coated tablets containing 25 mg of exemestane as the active ingredient. Exemestane is an irreversible, steroidal aromatase inactivator, structurally related to the natural substrate androstenedione. In postmenopausal women, estrogens are produced primarily from the conversion of androgens into estrogens through the aromatase enzyme in peripheral tissues, and estrogen deprivation through aromatase inhibition is an effective and selective treatment for hormone dependent breast cancer in postmenopausal women.

Approved indications —

Sequential adjuvant treatment of estrogen receptor positive early breast cancer in postmenopausal women who have received prior adjuvant tamoxifen therapy. — Treatment of estrogen receptor positive advanced breast cancer in women with natural or induced postmenopausal status whose disease has progressed following antiestrogen therapy.

Dosing overview

The recommended dose of exemestane in adults is one 25 mg tablet taken once daily, preferably after a meal. In patients with early breast cancer, treatment should continue until completion of five years adjuvant hormonal therapy or until tumour relapse occurs. In patients with advanced breast cancer, treatment with exemestane should continue until tumour progression is evident. No dose adjustments are required for patients with renal insufficiency or hepatic insufficiency.

Key safety warnings

Because of its mode of action, exemestane should not be administered to women with pre-menopausal endocrine status. Whenever clinically appropriate, confirmation of postmenopausal status may be assisted by laboratory tests, such as assessment of luteinising hormone (LH), follicle stimulating hormone (FSH) and oestradiol levels. Routine assessment of 25 hydroxy vitamin D levels prior to the start of aromatase inhibitor treatment should be considered, due to the high prevalence of severe deficiency associated in women with early breast cancer. Women with Vitamin D deficiency should receive supplementation with Vitamin D. In trial 031, the incidence of fracture was greater in patients treated with exemestane than tamoxifen. Treatment-emergent fractures were more frequent in exemestane patients (4.5%) than in tamoxifen patients (3.3%). When all fractures reported on-treatment and during follow-up are considered, the incidence was significantly greater in exemestane patients (7.3%) compared with tamoxifen patients (5.2%). Reductions in bone mineral density (BMD) over time are seen with exemestane use. During adjuvant treatment with exemestane, women with osteoporosis or at risk of developing osteoporosis should have their bone mineral density formally assessed by bone densitometry at the commencement of treatment and at regular intervals thereafter. Treatment or prophylaxis for osteoporosis should be initiated as appropriate and carefully monitored. The use of third generation aromatase inhibitors, including exemestane, were found to be associated with tendonitis and tenosynovitis in randomised controlled trials. Tendon rupture was found to be a potential risk associated with third generation aromatase inhibitors. Monitor patients for signs and symptoms of tendon disorders during treatment with exemestane.

Contraindications

Exemestane tablets are contraindicated in pregnant or lactating women and patients with a known hypersensitivity to the drug or to any of the excipients.

PBS listing

The 25 mg tablet is listed on the PBS with restriction, with an ex-manufacturer price of A$37.73.

Regulatory history

AROMASIN exemestane 25 mg tablet was first listed on the ARTG on 30 November 2000. The first approval date for the APO-Exemestane product was 6 October 2011.