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letrozole (Femara)

Tradename: Femara. Indications: 1) treatment of breast cancer in postmenopausal women a) treatment of advanced breast cancer in postmenopausal women with disease progression following antiestrogen (tamoxifen) therapy b) prophylaxis of recurrent breast cancer in patients having completed 5 years of tamoxifen therapy [4] c) in general aromatase inhibitors 1st line therapy in postmenopausal women 2) ovarian cancer [6] 3) promoting ovulation & facilitating pregnancy in women with polycystic ovary syndrome [7] Dosage: - 2.5 mg QD [4] - estrogen receptor positive breast cancer - intermittent letrozole (2.5 mg/day for 9 months, followed by 3-month break for years 1 to 4; then daily treatment in year 5) with similar outcomes to continuous daily treatment [8] Pharmacokinetics: -> dimimishes estrogen levels by 95% in postmenopausal women Adverse effects: 1) osteoporosis* 2) hot flashes 3) arthralgia 4) myalgia 5) sexual dysfunction 6) dyslipidemia (low-grade) 7) adverse cardiovascular events (generally not severe) a) iliac artery stenosis b) intermittent claudication c) aortic dilatation d) hypertensive angiopathy * consider concurrent Ca+2, vitamin D & bisphosphonate treatment Mechanism of action: -> inhibits biosynthesis of estradiol by inhibition of aromatase

Interactions

drug adverse effects of aromatase inhibitors

Related

cytochrome P450 19A1 (aromatase, estrogen synthetase, CYP19A1)

General

antineoplastic endocrine agent aromatase inhibitor

Properties

INHIBITS: cytochrome P450 19A1

Database Correlations

PUBCHEM cid=3902

References

  1. Kaiser Permanente Northern California Regional Drug Formulary, Update 9/99
  2. Prescriber's Letter 8(2):10 2001
  3. Prescriber's Letter 10(11):64 2003
  4. Journal Watch 23(22):173, 2003 Goss PE et al, N Engl J Med 349:1793, 2003 http://content.nejm.org/cgi/reprint/NEJMoa032312v1.pdf PMID: 14551341 Bryant J & Wolmark N, N Engl J Med 349:1855, 2003 Burnstein HJ, N Engl J Med 349:1857, 2003
  5. Coates AS, Keshaviah A, Thurlimann B, Mouridsen H, Mauriac L, Forbes JF, Paridaens R, Castiglione-Gertsch M, Gelber RD, Colleoni M, Lang I, Del Mastro L, Smith I, Chirgwin J, Nogaret JM, Pienkowski T, Wardley A, Jakobsen EH, Price KN, Goldhirsch A. Five years of letrozole compared with tamoxifen as initial adjuvant therapy for postmenopausal women with endocrine- responsive early breast cancer: update of study BIG 1-98. J Clin Oncol. 2007 Feb 10;25(5):486-92. Epub 2007 Jan 2. PMID: 17200148
  6. Deprecated Reference
  7. Legro RS et al Letrozole versus Clomiphene for Infertility in the Polycystic Ovary Syndrome. N Engl J Med 2014; 371:119-129. July 10, 2014 PMID: 25006718 http://www.nejm.org/doi/full/10.1056/NEJMoa1313517
  8. Colleoni M, Luo W, Karlsson P et al Extended adjuvant intermittent letrozole versus continuous letrozole in postmenopausal women with breast cancer (SOLE): a multicentre, open-label, randomised, phase 3 trial. The Lancet Oncology. Nov 17, 2017 PMID: 29158011 http://thelancet.com/journals/lanonc/article/PIIS1470-2045(17)30715-5/fulltext - Chlebowski RT, Pan K. Complexity of intermittent letrozole adjuvant therapy. The Lancet Oncology. Nov 17, 2017 PMID: 29158010 http://thelancet.com/journals/lanonc/article/PIIS1470-2045(17)30854-9/fulltext

Component-of

letrozole/ribociclib (Femara/Kisqali)