Letrozole

Brand names: Femara®

Chemical formula:

Español:
• Letrozol, Tableta oral

Letrozole Oral tablet

What is this medicine?

LETROZOLE (LET roe zole) blocks the production of estrogen. Certain types of breast cancer grow under the influence of estrogen. Letrozole helps block tumor growth. This medicine is used to treat advanced breast cancer in postmenopausal women.
 
This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
•liver disease
•osteoporosis (weak bones)
•an unusual or allergic reaction to letrozole, other medicines, foods, dyes, or preservatives
•pregnant or trying to get pregnant
•breast-feeding

How should I use this medicine?

Take this medicine by mouth with a glass of water. You may take it with or without food. Follow the directions on the prescription label. Take your medicine at regular intervals. Do not take your medicine more often than directed. Do not stop taking except on your doctor's advice.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
NOTE: This medicine is only for you. Do not share this medicine with others.

What may interact with this medicine?

Do not take this medicine with any of the following medications:
•estrogens, like hormone replacement therapy or birth control pills

This medicine may also interact with the following medications:
•dietary supplements such as androstenedione or DHEA
•prasterone
•tamoxifen

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medicine?

Visit your doctor or health care professional for regular check-ups to monitor your condition.

Do not use this drug if you are pregnant. Serious side effects to an unborn child are possible. Talk to your doctor or pharmacist for more information.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:
•allergic reactions like skin rash, itching, or hives
•bone fracture
•chest pain
•difficulty breathing or shortness of breath
•severe pain, swelling, warmth in the leg
•unusually weak or tired
•vaginal bleeding

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
•bone, back, joint, or muscle pain
•dizziness
•fatigue
•fluid retention
•headache
•hot flashes, night sweats
•nausea
•weight gain

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medicine?

Keep out of the reach of children.

Store between 15 and 30 degrees C (59 and 86 degrees F). Throw away any unused medicine after the expiration date.

Last updated: 7/1/2002

Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.

Letrozole
Systematic (IUPAC) name
4-[(4-cyanophenyl)-(1,2,4-triazol-1-yl)methyl]benzonitrile
Identifiers
CAS number	112809-51-5
ATC code	L02BG04
PubChem	3902
DrugBank	APRD01066
ChemSpider	3765
Chemical data
Formula	C17H11N5
Mol. mass	285.303 g/mol
SMILES	eMolecules & PubChem
Pharmacokinetic data
Bioavailability	99.9%
Protein binding	60%, mainly to albumin
Metabolism	?
Half life	2 days
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status	?(CA)
Routes	?
Y(what is this?)  (verify)

Letrozole (INN, trade name Femara) is an oral non-steroidal aromatase inhibitor that has been introduced for the adjuvant treatment of hormonally-responsive breast cancer.

Estrogens are produced by the conversion of androgens through the activity of the aromatase enzyme. Letrozole blocks production of estrogens in this way by competitive, reversible binding to the heme of its cytochrome P450 unit. The action is specific, and letrozole does not reduce production of mineralo- or corticosteroids. In contrast, the antiestrogenic action of tamoxifen, the major medical therapy prior to the arrival of aromatase inhibitors, is due to its interfering with the estrogen receptor, rather than inhibiting estrogen production.

Contents 1 FDA-approved use 2 Off-label use 3 References 4 See also 5 External links

FDA-approved use

Letrozole is approved by the United States Food and Drug Administration (FDA) for the treatment of local or metastatic breast cancer that is hormone receptor positive or has an unknown receptor status in postmenopausal women. Side effects include signs and symptoms of hypoestrogenism. There is concern that long term use may lead to osteoporosis, which is why prescriptions of Letrozole are often accompanied by prescriptions of osteoporosis-fighting medications such as bisphosphonates.

Off-label use

It has been used for ovarian stimulation by fertility doctors since 2001; having less side-effects than clomiphene citrate (Clomid) for the patient and may be it possess less risk for multiple gestation. A Canadian study presented at the American Society of Reproductive Medicine 2005 Conference suggests that it may increase the risk of birth defects compared with a control group, however a more detailed follow-up study found no basis for concern when letrozole is used for ovulation induction.^[1]

The manufacturer, Novartis, has issued letters to doctors in Canada and the United States reiterating that it is not approved for such a use and is not safe to use with pregnant women or women who may become pregnant.

Letrozole has shown to reduce estrogen levels by 98 percent while raising testosterone levels.^{[citation needed]} The anti-estrogen action of letrozole is preferred by athletes and bodybuilders for use during a steroid cycle to reduce bloating due to excess water retention and prevent the formation of gynecomastia related breast tissue that is a side effect of some anabolic steroids.^[2] Above 5mg/day for extended periods may cause kidney problems.^{[citation needed]}

Some studies have shown that Letrozole can be used to promote spermatogenesis in male patients suffering from nonobstructive azoospermia. ^[3]

Letrozole has also been shown to delay the fusing of the growth plates in adolescents. This may boost the effectiveness of growth hormone, and thus Letrozole is used to treat adolescents and children with short stature.^{[citation needed]}

A related agent is anastrozole.

Letrozole has also been used to treat endometriosis.^[4]

References

1. ^ Tulandi T, Martin J, Al-Fadhli R, Kabli N, Forman R, Hitkari J, Librach C, Greenblatt E, Casper RF. Congenital malformations among 911 newborns conceived after infertility treatment with letrozole or clomiphene citrate. Fertil Steril. 2006 Apr 28. PMID 16650422
2. ^ Gynecomastia-Gyno.com: Realistic Treatment Options
3. ^ Use of the aromatase inhibitor letrozole to treat male infertility Geneviève Patry, Keith Jarvi, Ethan D. Grober, Kirk C. Lo Fertility and Sterility August 2009 (Vol. 92, Issue 2, Pages 829.e1-829.e2)
4. ^ Endometriosis ESHRE abstract

See also

• Aromatase inhibitor

External links

• Femara website

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