letrozole

Therapeutic Classification: antineoplastics

Pharmacologic Classification: aromatase inhibitors

Indications ⬆ ⬇

High Alert

First-line or second-line treatment of postmenopausal women with hormone receptor positive or hormone receptor unknown advanced breast cancer.
Adjuvant treatment of postmenopausal women with hormone receptor positive early breast cancer.
Extended adjuvant treatment of postmenopausal early breast cancer already treated with 5 yr of tamoxifen.

Action ⬆ ⬇

Inhibits the enzyme aromatase, which is partially responsible for conversion of precursors to estrogen.

Therapeutic effects:

Lowers levels of circulating estrogen, which may halt progression of estrogen-sensitive breast cancer.
Decreased risk of recurrence/metastatic disease.

Pharmacokinetics ⬆ ⬇

Absorption: Rapidly and completely absorbed.

Distribution: Well distributed to tissues.

Metabolism/Excretion: Mostly metabolized by the liver. Primarily excreted in the urine (90%), with 6% being excreted as unchanged drug.

Half-Life: 2 days.

Time/Action Profile ⬆ ⬇

(effect on lowering of serum estradiol concentrations)

ROUTE	ONSET	PEAK	DURATION
PO	unknown	2–3 days	unknown

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Premenopausal women;
OB: Pregnancy;
Lactation: Lactation.

Use Cautiously in:

Severe hepatic impairment;
Rep: Women of reproductive potential;
Pedi: Safety and effectiveness not established in children.

Adv. Reactions/Side Effects ⬆ ⬇

CV: chest pain, DEEP VEIN THROMBOSIS, edema, hypertension

Derm: ↑sweating, alopecia, hot flush, pruritus, rash

F and E: hypercalcemia

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

GU: ↓fertility

Metab: hypercholesterolemia, weight gain

MS: musculoskeletal pain, ↓bone density, arthralgia, fracture

Neuro: anxiety, depression, dizziness, drowsiness, fatigue, headache, STROKE/TIA, vertigo, weakness

Resp: cough, dyspnea, pleural effusion, PULMONARY EMBOLISM

Interactions ⬆ ⬇

Drug-drug:

None reported.

Route/Dosage ⬆ ⬇

PO (Adults ): 2.5 mg once daily.

Hepatic Impairment

PO (Adults ): Severe hepatic impairment: 2.5 mg every other day.

Availability ⬆ ⬇

(Generic available)

Tablets: 2.5 mg

Assessment ⬆ ⬇

Assess patient for pain and other side effects periodically during therapy.
Monitor bone mineral density periodically during therapy.

Lab Test Considerations:

Verify negative pregnancy test before starting therapy.May cause elevated AST, ALT, alkaline phosphatase, bilirubin, GGT and cholesterol levels.

Implementation ⬆ ⬇

PO: May be taken without regard to food.

Patient/Family Teaching ⬆ ⬇

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.
Rep: May cause fetal harm. Advise females of reproductive potential to use effective contraception and to avoid breastfeeding during and for at least 3 wk after last dose of letrozole. May impair fertility in males and females. Caution women who are perimenopausal or who recently became menopausal to use adequate contraception during therapy.

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Pronunciation ⬇

Classifications ⬆ ⬇