letrozole

Action

Inhibits aromatase, an enzyme that promotes conversion of estrogen precursors to estrogen. This inhibition reduces circulating estrogen levels and stops progression of breast cancer.

Availability

Tablets: 2.5 mg

Indications and dosages

➣ Metastatic or advanced breast cancer in postmenopausal women; early breast cancer in postmenopausal women who have received 5 years of antiestrogen therapy

Adults: 2.5 mg P.O. daily

Contraindications

• Hypersensitivity to drug or its components

Precautions

Use cautiously in:

• severe hepatic impairment

• pregnant or breastfeeding patients

• children (safety not established).

Administration

• Give with or without meals.

Adverse reactions

CNS: anxiety, depression, dizziness, drowsiness, fatigue, headache, vertigo, asthenia

CV: chest pain, hypertension

EENT: blurred vision

GI: nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, anorexia

Metabolic: hypercalcemia

Musculoskeletal: musculoskeletal or joint pain, fractures

Respiratory: cough, dyspnea, pleural effusion

Skin: alopecia, pruritus, rash, diaphoresis

Other: hot flashes, edema, weight gain, angioedema, anaphylactic reactions

Interactions

Drug-diagnostic tests. Cholesterol, gamma-glutamyltransferase: increased levels

Patient monitoring

• Check vital signs and assess cardiovascular and respiratory status.

• Monitor renal and hepatic function, electrolyte levels, and lipid panels.

• Assess for adverse CNS effects, including depression. Institute safety measures as needed to prevent injury.

Patient teaching

• Tell patient she can take with or without food.

• Instruct patient to weigh herself regularly and report significant changes.

• Advise patient and family to watch for signs and symptoms of depression.

• Tell patient to minimize GI upset by eating small, frequent servings of healthy food and drinking plenty of fluids.

• Caution patient to avoid driving and other hazardous activities until she knows how drug affects concentration and alertness.

• Inform patient that treatment is long term. Urge her to keep follow-up appointments with prescriber.

• Tell patient to inform prescriber if she is pregnant or breastfeeding.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the tests mentioned above.