LETROZOLE
| LETROZOLE (le'tro-zole) Femara Classifications: antineoplastic; aromatase inhibitor; Therapeutic: antineoplastic; aromatase inhibitor Prototype: Anastrozole Pregnancy Category: D |
Availability
2.5 mg tablets
Action
Nonsteroid competitive inhibitor of aromatase, the enzyme that converts androgens to estrogens. It does not inhibit adrenal steroid synthesis.
Therapeutic Effect
Results in the regression of estrogen-dependent tumors.
Uses
Advanced breast cancer in postmenopausal women following antiestrogen therapy, first-line treatment of locally advanced or metastasized breast cancer in postmenopausal women.
Contraindications
Hypersensitivity to letrozole; pregnancy (category D), pregnant women, women of childbearing age, premenopausal females, hormone replacement therapy (HRT).
Cautious Use
Moderate to severe hepatic impairment; lactation. Safety and efficacy in children are not established.
Route & Dosage
| Breast Cancer Adult: PO 2.5 mg q.d. Hepatic Impairment Reduce the dose in severe hepatic impairment (Child-Pugh C class) by 50%. |
Administration
Oral- Give without regard to food.
Adverse Effects (≥1%)
Body as a Whole: Fatigue, peripheral edema, asthenia, weight increase, musculoskeletal pain, arthralgia. CNS: Headache, somnolence, dizziness. CV: Chest pain, hypertension, hypercholesterolemia. GI: Nausea, vomiting, constipation, diarrhea, abdominal pain, anorexia, dyspepsia. Respiratory: Dyspnea, cough. Skin: Hot flushes, rash, pruritus.Interactions
Drug: estrogens, oral contraceptives could interfere with the pharmacologic action of letrozole.Pharmacokinetics
Absorption: Rapidly absorbed from GI tract. Metabolism: In liver by cytochromes P450 3A4 and 2A6. Elimination: 90% in urine. Half-Life: 2 d.Nursing Implications
Assessment & Drug Effects
- Lab tests: Periodically monitor serum calcium and CBC with differential.
- Monitor carefully for S&S of thrombophlebitis or thromboembolism; report immediately.
Patient & Family Education
- Notify physician immediately if S&S of thrombophlebitis develop (see Appendix F).
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; 
Canadian drug name; 
Prototype drug