Dosing & Uses
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
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
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 (6)
- 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.
- mavacamten
letrozole will increase the level or effect of mavacamten by affecting hepatic enzyme CYP2C19 metabolism. Modify Therapy/Monitor Closely. Inititiation of weak CYP2C19 inhibitors may require decreased mavacamten dose.
- 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)
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
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
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.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%
Administration
Oral Administration
May take with or without food
Images
| BRAND | FORM. | UNIT PRICE | PILL IMAGE |
|---|---|---|---|
| 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 |  | |
| Femara oral - | 2.5 mg tablet |  |
Copyright © 2010 First DataBank, Inc.
Patient Handout
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 if available from your pharmacist before you start using letrozole and each time you get a refill. If you have any questions, ask your doctor or pharmacist.Take this medication by mouth with or without food as directed by your doctor, usually once daily.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 pain/stiffness/swelling, bone/muscle pain, tiredness, unusual sweating, nausea, diarrhea, dizziness, and trouble sleeping may occur. If any of these effects last or get worse, tell 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: nausea/vomiting that doesn't stop, bone fractures, mental/mood changes (such as depression, anxiety), swelling of arms/legs, blurred vision, 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.Lab and/or medical tests (such as bone density tests, cholesterol levels, liver function) should be done while you are taking this medication. Keep all medical and lab appointments. 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 May 2023. Copyright(c) 2023 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.
Formulary
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