letrozole (Rx)

Brand and Other Names:Femara
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablet

  • 2.5mg

Breast Cancer

Adjuvant treatment of early breast cancer

  • Postmenopausal women with hormone receptor positive early breast cancer
  • 2.5 mg PO qDay

Extended adjuvant treatment of early breast cancer

  • Postmenopausal women, who have received 5 yr of adjuvant tamoxifen therapy
  • 2.5 mg PO qDay

First and second-line treatment of advanced breast cancer

  • Postmenopausal women with hormone receptor positive or unknown, locally advanced or metastatic breast cancer
  • Also indicated for treatment of advanced breast cancer in postmenopausal women with disease progression following antiestrogen therapy
  • 2.5 mg PO qDay; continue until tumor progression is evident

Dosing Considerations

Effectiveness of letrozole in extended adjuvant treatment of early breast cancer is based on an analysis of disease-free survival in patients treated for a median of 60 months

Dosage Modifications

Renal impairment

  • Mild-to-moderate (CrCl ≥30 mL/min): No dose adjustment necessary
  • Severe (CrCl ≥10 to <30 mL/min): No dose adjustment necessary

Hepatic impairment

  • Mild-to-moderate: No dose adjustment necessary
  • Patients with cirrhosis and severe hepatic dysfunction: Reduce dose by 50% (ie, 2.5 mg every other day)
  • Noncirrhotic patients with elevated bilirubin levels have not been studied

Ovarian Epithelial Cancer (Off-label)

2.5 mg PO qDay

Safety and efficacy not established

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Interactions

Interaction Checker

and letrozole

No Results

     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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             activity indicator 

            Contraindicated (0)

              Serious - Use Alternative (2)

              • ethinylestradiol

                ethinylestradiol decreases effects of letrozole by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Letrozole should not be given concurrently with any estrogens or estrogen-containing products.

              • tamoxifen

                tamoxifen decreases levels of letrozole by unspecified interaction mechanism. Contraindicated. Letrozole should not be given concurrently with tamoxifen. Letrozole therapy after the completion of standard tamoxifen treatment is not associated with impaired effects of letrozole.

              Monitor Closely (5)

              • cholera vaccine

                letrozole decreases effects of cholera vaccine by immunosuppressive effects; risk of infection. Modify Therapy/Monitor Closely. Immunosuppressive therapies, including irradiation, antimetabolites, alkylating agents, cytotoxic drugs and corticosteroids (used in greater than physiologic doses), may reduce the immune response to cholera vaccine.

              • dengue vaccine

                letrozole decreases effects of dengue vaccine by immunosuppressive effects; risk of infection. Use Caution/Monitor. Immunosuppressive therapies (eg, irradiation, antimetabolites, alkylating agents, cytotoxic drugs, corticosteroids [greater than physiologic doses]) may reduce immune response to dengue vaccine.

              • eluxadoline

                letrozole increases levels of eluxadoline by decreasing metabolism. Use Caution/Monitor. As a precautionary measure due to incomplete information on the metabolism of eluxadoline, use caution when coadministered with strong CYP2A6 inhibitors.

              • letermovir

                letermovir increases levels of letrozole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

              • siponimod

                siponimod and letrozole both increase immunosuppressive effects; risk of infection. Use Caution/Monitor. Caution if coadministered because of additive immunosuppressive effects during such therapy and in the weeks following administration. When switching from drugs with prolonged immune effects, consider the half-life and mode of action of these drugs to avoid unintended additive immunosuppressive effects.

              Minor (0)

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                Adverse Effects

                >10%

                Diaphoresis (24%)

                Bone pain (22%)

                Hot flashes (19%)

                Back pain (18%)

                Dyspnea (18%)

                Nausea (17%)

                Night sweats (14%)

                Cough (13%)

                Fatigue (13%)

                1-10%

                Constipation (10%)

                Hypertension (8%)

                Chest pain (8%)

                Diarrhea (8%)

                Decr wt (7%)

                Edema (7%)

                Breast pain (7%)

                Bone fractures (6%)

                UTI (6%)

                Hypercalcemia (5%)

                Headache (4%)

                Weakness (4%)

                Vomiting (3%)

                Osteoporosis (2%)

                <1%

                Blurred vision

                Increased hepatic enzyme levels

                Postmarketing Reports

                Blurred vision

                Increased hepatic enzymes

                Hepatitis

                Angioedema

                Anaphylactic reactions

                Toxic epidermal necrolysis

                Erythema multiforme

                Carpal tunnel syndrome

                Trigger finger

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                Warnings

                Contraindications

                Hypersensitivity to drug or excipients

                Pregnancy, premenopausal women

                Cautions

                Use caution in liver impairment; administer a low dose to patients with hepatic impairment; effect of hepatic impairment on drug exposure in cancer patients with elevated bilirubin levels not determined

                Decreases in bone mineral density may occur; consider bone mineral density monitoring; increased risk of osteoporosis

                May cause dizziness, somnolence and fatigue; exercise caution when operating machinery

                May increase total serum cholesterol; consider cholesterol monitoring

                Avoid concomitant estrogens

                Risk of birth defects if given to pregnant women

                • Used off-label to induce ovulation
                • Health Canada & Novartis Canada warned against such use
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                Pregnancy & Lactation

                Pregnancy

                Based on post-marketing reports, findings from animal studies and mechanism of action, therapy can cause fetal harm and is contraindicated for use in pregnant women; in post-marketing reports, use during pregnancy resulted in cases of spontaneous abortions and congenital birth defects; however, data are insufficient to inform a drug-associated risk

                Contraception

                • Advise females of reproductive potential to use effective contraception during treatment and for at least 3 weeks after last dose

                Infertility

                • Therapy may impair fertility in females and males of reproductive potential

                Lactation

                Not known if therapy is present in human milk; there are no data on effects on breastfed infant or milk production; exposure of lactating rats to drug was associated with impaired reproductive performance of male offspring; because of potential for serious adverse reactions in breastfed infants, advise lactating women not to breastfeed while receiving therapy and for at least 3 weeks after last dose

                Pregnancy Categories

                A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

                B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

                C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

                D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

                X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

                NA: Information not available.

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                Pharmacology

                Mechanism of Action

                Aromatase inhibitor - blocks conversion of androgens to estrogens by binding to the heme group of aromatase enzyme, which in turn inhibits its activity

                Distribution

                Vd: 1.9 L/kg

                Metabolism

                Metabolites: 4,4'-methanol-bisbenzonitrile via CYP3A4 and 2A6 activity

                Enzymes inhibited: Aromatase

                Elimination

                Half-life: 2 days

                Excretion: Urine 90%

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                Administration

                Oral Administration

                May take with or without food

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                Images

                BRAND FORM. UNIT PRICE PILL IMAGE
                Femara oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet
                letrozole oral
                -
                2.5 mg tablet

                Copyright © 2010 First DataBank, Inc.

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                Patient Handout

                Patient Education
                letrozole oral

                LETROZOLE - ORAL

                (LET-tro-zole)

                COMMON BRAND NAME(S): Femara

                USES: This medication is used to treat certain types of breast cancer (such as hormone-receptor-positive breast cancer) in women after menopause. Letrozole is also used to help prevent the cancer from returning. Some breast cancers are made to grow faster by a natural hormone called estrogen. Letrozole decreases the amount of estrogen the body makes and helps to slow or reverse the growth of these breast cancers.

                HOW TO USE: Read the Patient Information Leaflet provided by your pharmacist before you start using letrozole and each time you get a refill. If you have any questions, consult your doctor or pharmacist.Take this medication by mouth, usually once daily with or without food or as directed by your doctor.Dosage is based on your medical condition and response to treatment.Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day.Since this drug can be absorbed through the skin and lungs, women who are pregnant should not handle this medication or breathe the dust from the tablets. (See also Precautions section.)Inform your doctor right away if your condition worsens (such as you get new breast lumps).

                SIDE EFFECTS: Hot flashes, hair loss, joint/bone/muscle pain, tiredness, unusual sweating, nausea, diarrhea, dizziness, and trouble sleeping may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: bone fractures, mental/mood changes (such as depression, anxiety), swelling of arms/legs, blurred vision, persistent nausea/vomiting, unusual tiredness, dark urine, yellowing eyes/skin..This medication (and cancer) may rarely cause serious problems from blood clots (such as heart attack or stroke). Get medical help right away if you experience: sudden shortness of breath, chest/jaw/left arm pain, confusion, coughing up blood, sudden dizziness/fainting, pain/swelling/warmth in the groin/calf, tingling/weakness/numbness in the arms/legs, trouble speaking, weakness on one side of the body, vision changes, sudden/severe headache.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat/neck), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

                PRECAUTIONS: Before taking letrozole, tell your doctor or pharmacist if you are allergic to it; or to anastrozole; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: high blood fats (cholesterol), bone problems (such as osteopenia, osteoporosis), stroke or blood clots, heart disease (such as chest pain, heart attack, heart failure), high blood pressure, kidney problems, liver problems.This drug may make you dizzy or tired or rarely blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or tired. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).This medication must not be used during pregnancy. It may harm an unborn baby. Letrozole is used mainly in women after menopause. If you have recently gone through menopause, discuss the need for use of reliable forms of birth control while taking this medication and for 3 weeks after stopping treatment with your doctor. Do not use birth control products containing estrogen. Consult your doctor for more details. If you become pregnant or think you may be pregnant, tell your doctor right away. (See also How to Use section.)It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breast-feeding while using this drug and for at least 3 weeks after stopping treatment is not recommended. Consult your doctor before breast-feeding.

                DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: estrogens (such as ethinyl estradiol, conjugated estrogens), estrogen blockers (such as anastrozole, tamoxifen), tibolone.

                OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

                NOTES: Do not share this medication with others.Laboratory and/or medical tests (such as bone density tests, cholesterol levels, liver function tests) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.This medication can increase the risk of bone loss (osteoporosis). Talk with your doctor about your risk, and about available treatments for osteoporosis. Lifestyle changes that reduce the risk of bone loss include doing weight-bearing exercise, getting enough calcium and vitamin D, stopping smoking, and limiting alcohol.

                MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

                STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

                Information last revised August 2021. Copyright(c) 2021 First Databank, Inc.

                IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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                Formulary

                FormularyPatient Discounts

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                • View the formulary and any restrictions for each plan.
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                • Compare formulary status to other drugs in the same class.
                • Access your plan list on any device – mobile or desktop.

                The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

                Tier Description
                1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
                2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
                3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
                4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
                5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
                6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
                NC NOT COVERED – Drugs that are not covered by the plan.
                Code Definition
                PA Prior Authorization
                Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
                QL Quantity Limits
                Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
                ST Step Therapy
                Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
                OR Other Restrictions
                Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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                Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.