Exemestane

Oral
Adjuvant therapy for postmenopausal women with hormone receptor positive early breast cancer
Adult: Following 2-3 yr initial adjuvant tamoxifen treatment, 25 mg once daily for a total of 5 yr of combined sequential adjuvant hormonal therapy; or earlier if tumour relapse occurs.

Oral
Advanced or locally advanced breast cancer
Adult: 25 mg once daily continued until evident tumour progression.

Special Populations: Patients on strong CYP3A4 enzyme inducers: 50 mg once daily.

Should be taken with food.

Premenopausal women. Pregnancy and lactation.

Patient w/ uncontrolled HTN, osteoporosis and its potential causes (e.g. vit D deficiency, hyperthyroidism, hyperparathyroidism). Hepatic and renal impairment. Patient Counselling This drug may cause drowsiness, asthenia, and dizziness, if affected, do not drive or operate machinery. Monitoring Parameters Monitor 25-hydroxy vit D level and BMD prior to therapy; and LFT. Assess for new or unusual bone pain or swelling of face, lips, or throat.

Significant: Decrease in BMD. Nervous: Headache, dizziness, depression, insomnia, anxiety, neuropathy, paraesthesia. CV: HTN. GI: Diarrhoea, nausea, abdominal pain, anorexia, constipation, vomiting. Resp: Dyspnoea. Musculoskeletal: Arthralgia, myalgia, carpal tunnel syndrome, osteoarthritis, osteoporosis. Ophthalmologic: Visual disturbances. Dermatologic: Hot flushes, alopecia, increased sweating, dermatitis, peripheral eodema, rash. Others: Fatigue.

Decreased plasma levels of exemestane when used w/ strong CYP3A4 enzyme inducers (e.g. phenytoin, carbamazepine, rifampicin). Antagonised effect w/ oestrogens.

Increased bioavailability w/ food. Decreased therapeutic effect w/ St John's wort.

Exemestane is an irreversible, selective aromatase inhibitor which acts as a false substrate for the enzyme and forms an intermediate that binds to its active site. This leads to inactivation or suicide inhibition, thus preventing the conversion of androgens to oestrogens in peripheral tissues. It lowers circulating oestrogens in postmenopausal women w/ breast cancers where growth is oestrogen-dependent.
Absorption: Rapidly absorbed from the GI tract. Time to peak plasma concentration: 1.2 hr.
Distribution: Extensively distributed into tissues; crosses the placenta. Plasma protein binding: 90%, primarily to albumin and α₁-acid glycoprotein.
Metabolism: Metabolised via oxidation by CYP3A4 enzyme and via reduction by aldoketoreductase into inactive metabolites.
Excretion: Via urine (<1% as unchanged drug; 39-45% as metabolites); faeces (36-48%). Elimination half-life: Approx 24 hr.

Oral: Store between 20-25°C.

Hormonal Chemotherapy

L02BG06 - exemestane ; Belongs to the class of enzyme inhibitors. Used in endocrine therapy.