Letrozole

A to Z Drug Facts

 Action A nonsteroidal competitive inhibitor of the aromatase enzyme system; it inhibits the conversion of androgens to estrogens. Elimination half-life is approximately 2 days. It is weakly protein bound. Renal excretion is the major pathway of letrozole clearance.

 Indications Advanced breast cancer in postmenopausal women with disease progression following antiestrogen therapy; first-line treatment of postmenopausal women with hormone receptor positive or hormone receptor unknown locally advanced or metastatic cancer.

 Contraindications Standard considerations.

 Route/Dosage

Breast Cancer Adults: PO 2.5 mg once daily (tablets).

 Interactions

Contraceptives, oral May alter the efficacy of oral contraceptives.

Tamoxifen Plasma concentrations of letrozole may be decreased.

 Lab Test Interferences None well documented.

 Adverse Reactions

CARDIOVASCULAR: Chest pain; hypertension; peripheral edema. CNS: Decreased appetite; fatigue; headache; insomnia; somnolence; dizziness; asthenia; weakness. DERMATOLOGIC: Rash; pruritis; alopecia. GI: Nausea and vomiting; constipation; diarrhea; abdominal pain; anorexia; dyspepsia. GU: Sexual inactivity; atrophy of the female reproductive organs; breast pain. METABOLIC: Hot flashes; weight gain; hypercholesterolemia; weight loss. RESPIRATORY: Dyspnea; coughing. OTHER: Viral infections; musculoskeletal pain; arthralgia; flu-like symptoms.

 Precautions

Pregnancy: Category D. Lactation: Undetermined. Children: Safety and efficacy not established. Hepatic function impairment: Use caution in patients with severe hepatic dysfunction.

 Administration/Storage

• Store at controlled room temperature (59° and 86°F).
• Administer PO; may be taken without regard to meals.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note history of liver disease.
• Monitor for GI, CNS, musculoskeletal, and general body side effects. Inform health care provide if noted and significant.

 Patient/Family Education

• Explain name, dose, action, and potential side effects of drug.
• Review dosing schedule with patient.
• Advise patient that medication can be taken without regard to meals, but to take with food if GI upset occurs.
• Advise patient that if a dose is missed, take it as soon as possible, but if close to the next dose, do not double the dose to catch up and take the next dose as scheduled.
• Advise patient to report persistent or intolerable side effects to health care provider.
• Instruct patient to not take any prescription or OTC medications or dietary supplements unless advised to do so by the health care provider.
• Advise patient that follow-up examinations and lab tests will be required to monitor therapy and to keep appointments.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts