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Indications and Dosage
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 breast cancer in postmenopausal women Adult: 25 mg once daily continued until evident tumour progression.
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Special Patient Group
Patients on strong CYP3A4 enzyme inducers: 50 mg once daily.
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Administration
Should be taken with food.
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Contraindications
Premenopausal women. Pregnancy and lactation.
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Special Precautions
Patient w/ uncontrolled HTN, osteoporosis and its potential causes (e.g. vit D deficiency, hyperthyroidism, hyperparathyroidism). Hepatic and renal impairment.
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Adverse Reactions
Significant: Decrease in BMD.
Nervous: Headache, dizziness, depression, insomnia, anxiety, neuropathy, paraesthesia. CV: HTN, peripheral oedema. 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, rash. Others: Fatigue. |
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Patient Counseling Information
This drug may cause drowsiness, asthenia, and dizziness, if affected, do not drive or operate machinery.
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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.
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Drug Interactions
Decreased plasma levels of exemestane when used w/ strong CYP3A4 enzyme inducers (e.g. phenytoin, carbamazepine, rifampicin). Antagonised effect w/ oestrogens.
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Food Interaction
Increased bioavailability w/ food. Decreased therapeutic effect w/ St John’s wort.
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Action
Description:
Mechanism of Action: 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. Pharmacokinetics: 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. |
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Chemical Structure
 Source: National Center for Biotechnology Information. PubChem Database. Exemestane, CID=60198, https://pubchem.ncbi.nlm.nih.gov/compound/Exemestane (accessed on Jan. 23, 2020) |
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Storage
Store between 20-25°C.
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MIMS Class
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ATC Classification
L02BG06 - exemestane ; Belongs to the class of enzyme inhibitors. Used in treatment of neoplastic diseases.
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References
Anon. Exemestane. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/03/2017. Buckingham R (ed). Exemestane. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/03/2017. Exemestane Tablet, Film Coated (West-Ward Pharmaceuticals Corp). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 01/03/2017. Joint Formulary Committee. Exemestane. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/03/2017. McEvoy GK, Snow EK, Miller J et al (eds). Exemestane. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 01/03/2017.
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