Overview
11 DESCRIPTION Letrozole tablet USP for oral administration contains 2.5 mg of letrozole, a nonsteroidal aromatase inhibitor (inhibitor of estrogen synthesis). It is chemically described as 4,4'-(1H-1,2,4-Triazol-1-ylmethylene) dibenzonitrile, and its structural formula is Letrozole is a white to yellowish crystalline powder, practically odorless, freely soluble in dichloromethane, slightly...
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action The growth of some cancers of the breast is stimulated or maintained by estrogens. Treatment of breast cancer thought to be hormonally responsive (i.e., estrogen and/or progesterone receptor positive or receptor unknown) has included a variety of efforts to decrease estrogen levels (ovariectomy, adrenalectomy, hypophysectomy) or inhibit estrogen effects (antiestrogens and progestational agents). These interventions lead to decreased tumor mass or delayed progression of tumor growth in some women. In postmenopausal women, estrogens are mainly derived from the action of the aromatase enzyme, which converts adrenal androgens (primarily androstenedione and testosterone) to estrone and estradiol.
Indications
- 1 INDICATIONS AND USAGE Letrozole tablet is an aromatase inhibitor indicated for: Adjuvant treatment of postmenopausal women with hormone receptor positive early breast cancer ( 1.1 ) Extended adjuvant treatment of postmenopausal women with early breast cancer who have received prior standard adjuvant tamoxifen therapy ( 1.2 ) First and second-line treatment of postmenopausal women with hormone receptor positive or unknown advanced breast cancer ( 1.3 ) 1.
Common Doses
- 2.5 mg
- 10 mL
Dosage
2 DOSAGE AND ADMINISTRATION Letrozole tablets are taken orally without regard to meals ( 2 ): Recommended dose: 2.5.mg once daily ( 2.1 ) Patients with cirrhosis or severe hepatic impairment: 2.5 mg every other day ( 2.5 , 5.3 ) 2.1 Recommended Dose The recommended dose of letrozole tablet is one 2.5 mg tablet administered once a day, without regard to meals. 2.2 Use in Adjuvant Treatment of Early Breast Cancer In the adjuvant setting, the optimal duration of treatment with letrozole is unknown.
Contraindications
- 4 CONTRAINDICATIONS Pregnancy: Letrozole can cause fetal harm [see Use in Specific Populations ( 8.1 )] . Pregnancy: Letrozole can cause fetal harm [see Use in Specific Populations ( 8.1 )] . Known hypersensitivity to the active substance, or to any of the excipients [see Adverse Reactions ( 6 )] . Known hypersensitivity to the active substance, or to any of the excipients [see Adverse Reactions ( 6 )] . Pregnancy ( 4 ) Known hypersensitivity to the active substance, or to any of the excipients ( 4 )
Side Effects
- 6 ADVERSE REACTIONS The following adverse reactions are discussed in greater detail in other sections of the labeling. Bone effects [see Warnings and Precautions ( 5.1 )] Increases in cholesterol [see Warnings and Precautions ( 5.2 )] Fatigue and Dizziness [see Warnings and Precautions ( 5.4 )] The most common adverse reactions (greater than 20%) were hot flashes, arthralgia; flushing, asthenia, edema, arthralgia, headache, dizziness, hypercholesterolemia, sweating increased, bone pain and musculoskeletal ( 6 ). To report SUSPECTED ADVERSE REACTIONS, contact Accord Healthcare Inc.
Interactions
- 7 DRUG INTERACTIONS Tamoxifen Coadministration of letrozole and tamoxifen 20 mg daily resulted in a reduction of letrozole plasma levels of 38% on average (study P015). Clinical experience in the second-line breast cancer trials (AR/BC2 and AR/BC3) indicates that the therapeutic effect of letrozole therapy is not impaired if letrozole is administered immediately after tamoxifen. Cimetidine A pharmacokinetic interaction study with cimetidine (study P004) showed no clinically significant effect on letrozole pharmacokinetics.