Letrax®
Letrozole
tablet
Breast cancer in postmenopausal patients: Adjuvant treatment of hormone receptor-positive early breast cancer.
Extended adjuvant treatment of early breast cancer after 5 years of adjuvant tamoxifen therapy.
First-line treatment of hormone receptor-positive or hormone receptor-unknown, locally-advanced or metastatic breast cancer.
Treatment of advanced breast cancer in patients with disease progression following antiestrogen therapy
Mechanism of Action:
Letrozole is a nonsteroidal competitive inhibitor of the aromatase enzyme system which binds to the heme group of aromatases, a cytochrome P450 enzyme which catalyzes conversion of androgens to estrogens (specifically, androstenedione to estrone and testosterone to estradiol). This leads to inhibition of the enzyme and a significant reduction in plasma estrogen (estrone, estradiol and estrone sulfate) levels. Letrozole does not appear to affect synthesis of adrenal or thyroid hormones, aldosterone, or androgens.
Method of Administration:
Early breast cancer, adjuvant treatment: Postmenopausal patients: Oral: 2.5 mg once daily for a planned duration of 5 years; discontinue at relapse.
Early breast cancer, extended adjuvant treatment: Postmenopausal patients: Oral: 2.5 mg once daily for a planned duration of 5 years (after 5 years of tamoxifen); discontinue at relapse.
Notes
Known hypersensitivity to letrozole or any component of the formulation; pregnancy
Interactions:
Methadone: Aromatase Inhibitors may increase the serum concentration of Methadone. Risk C: Monitor therapy
Nintedanib: Letrozole may increase the serum concentration of Nintedanib. Risk C: Monitor therapy
Tamoxifen: May decrease the serum concentration of Letrozole. Risk C: Monitor therapy
Pregnancy and Lactation:
Use is contraindicated in patients with an established pregnancy.
Due to the potential for serious adverse reactions in the breastfed infant, breastfeeding is not recommended during therapy and for at least 3 weeks after the letrozole last dose.
Warning and Precaution:
- CNS depression: May cause dizziness, fatigue, and somnolence; patients should be cautioned before performing tasks which require mental alertness (eg, operating machinery or driving).
- Increased cholesterol: May increase total serum cholesterol. In patients treated with adjuvant therapy and cholesterol levels within normal limits, an increase of ≥1.5 x ULN in total cholesterol (nonfasting) has been demonstrated in 8.2% of letrozole-treated patients (25% requiring lipid-lowering medications) versus 3.2% of tamoxifen-treated patients (16% requiring medications).
Adverse Reactions:
Cardiovascular: Edema (7% to 18%), flushing (50%)
Dermatologic: Diaphoresis (24%), night sweats (15%)
Endocrine & metabolic: Hot flash (19% to 34%), hypercholesterolemia (52%), weight gain (13%)
Gastrointestinal: Nausea (9% to 17%)
Nervous system: Dizziness (3% to 14%), fatigue (10% to 13%)
Storage:
Store below 30ºC and protect from light and moisture.