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Pharmacologic class: Aromatase inhibitor
Therapeutic class: Antineoplastic
Pregnancy risk category D
Inhibits aromatase, an enzyme that promotes conversion of estrogen precursors to estrogen. This inhibition reduces circulating estrogen levels and stops progression of breast cancer.
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
• Hypersensitivity to drug or its components
Use cautiously in:
• severe hepatic impairment
• pregnant or breastfeeding patients
• children (safety not established).
• Give with or without meals.
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
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
Drug-diagnostic tests. Cholesterol, gamma-glutamyltransferase: increased levels
• 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.
• 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.
Pharmacologic: aromatase inhibitors
Time/action profile (effect on lowering of serum estradiol levels)
Adverse Reactions/Side Effects
Central nervous system
- pleural effusion
- chest pain
- cerebrovascular events
- thromboembolic events
- nausea (most frequent)
- abdominal pain
- hot flashes
- ↑ sweating
Fluid and Electrolyte
- weight gain
- musculoskeletal pain (most frequent)
- ↓ bone density
Drug-Drug interactionNone significant.
Hepatic ImpairmentOral (Adults) Severe hepatic impairment—2.5 mg every other day.
Availability (generic available)
- Assess patient for pain and other side effects periodically throughout therapy.
- Lab Test Considerations: May cause elevated AST, ALT, alkaline phosphatase, bilirubin, GGT and cholesterol levels.
Potential Nursing DiagnosesAcute pain (Side Effects)
- Do not confuse Femara (letrozole) with Femhrt (ethinyl estradiol/norethindrone).
- Oral: May be taken without regard to food.
- Instruct patient to take medication as directed.
- May cause dizziness and fatigue. Caution patient to avoid driving and other activities requiring awareness until response to medication is known.
- Inform patient of potential for adverse reactions and advise her to notify health care professional if side effects are problematic.
- Caution women who are perimenopausal or who recently became menopausal to use adequate contraception during therapy; letrozole may cause fetal harm.
- Slowing of disease progression in women with advanced breast cancer.
- Decreased risk of recurrence/metastatic disease.