Femara: Uses, Dosage, Side Effects

These are known as oestrogen receptor positive or ER-positive breast cancers. Letrozole works by temporarily blocking the activity of an enzyme called aromatase, which the body uses to make estrogen in the ovaries and other tissues. Blocking aromatase decreases the amount of estrogen produced by the body and may stop the growth of cancer cells that need estrogen to grow. Letrozole is a type of hormone therapy called an aromatase inhibitor.

DRUG INTERACTIONS

With estrogen blocked, the cancer cells that feed off estrogen may not be able to survive. Letrozole is an oral, anti-estrogen drug that is used for treating postmenopausal women with breast cancer. The growth of some breast cancers in postmenopausal women is promoted by estrogens that circulate in the blood, and the adrenal glands are the main source of these circulating estrogens. Letrozole inhibits the enzyme in the adrenal glands (aromatase) that produces the estrogens, estradiol and estrone. Your doctor or pharmacist can tell you more about the potential side effects of letrozole oral tablets. Some side effects of letrozole may occur that usually do not need medical attention.

Interactions with drugs or supplements

Moderate decreases in lymphocyte counts, of uncertain clinical significance, were observed in some patients receiving letrozole 2.5 mg. This depression was transient in about half of those affected. Two patients on letrozole developed thrombocytopenia; relationship to the study drug was unclear. Patient withdrawal due to laboratory abnormalities, whether related to study treatment or not was infrequent. At a median of 17 months of follow-up, three patients had a complete response, to the therapy, five a partial response, and sixteen had stable disease.

• Letrozole inhibits the aromatase enzyme by competitively binding to the heme of the cytochrome P450 subunit of the enzyme, resulting in a reduction of estrogen biosynthesis in all tissues.
• Femara is indicated for the extended adjuvant treatment of early breast cancer in postmenopausal women, who havereceived 5 years of adjuvant tamoxifen therapy.
• Plasma estradiol, estrone, and estrone sulfate reduced by 75–95% within 2–3 days with daily dosages of 0.1–5 mg.
• However, for those with unexplained causes of infertility, there does not appear to be a difference in the effectiveness of these two medications.

Certain adverse reactions were prospectively specified for analysis (see Table 1), based on the known pharmacologic properties andside effect profiles of the two drugs. If you have recently gone through menopause, discuss birth control with your doctor. It is unknown if this drug passes into breast milk and may harm a nursing infant. Letrozole may not be the best option if you take other medications that might interact with letrozole or affect your hormonal levels. Letrozole is safe for most people, but it can come with some side effects, which are typically mild and hormone-related. Letrozole is generally safe to take and doesn’t raise the risk of having a baby with birth defects.

Suppression is dose-related, with doses of 0.5 mg and higher giving many values of estrone and estrone sulfate that were below the limit of detection in the assays. Estrogen suppression was maintained throughout treatment in all patients treated at 0.5 mg or higher. Most adverse reactions reported (approximately 75% of patients who reported AEs) were Grade 1 or Grade 2 applying the Common Toxicity Criteria (CTC) Version 2.0/Common Terminology Criteria for Adverse Events (CTCAE), Version 3.0. Table 1 describes adverse reactions (Grades 1 to 4 and Grades 3 to 4) irrespective of relationship to study treatment in the adjuvant trial for the monotherapy arms analysis (safety population). Suppression is dose-related, with doses of 0.5 mg and higher giving many values of estrone and estrone sulfate that werebelow the limit of detection in the assays. Estrogen suppression was maintained throughout treatment in all patients treated at 0.5 mgor higher.

Based on studies in female animals, Femara may impair fertility in females of reproductive potential see Nonclinical Toxicology. The following adverse reactions have been identified during postapproval use of Femara. Because these reactions are reportedvoluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causalrelationship to drug exposure.

Femara is often given to women who have been taking tamoxifen (Nolvadex, Soltamox) for 5 years. Letrozole’s mechanism of action sets it apart from other common infertility medications, such as Clomid. And, unlike some fertility medications, letrozole is eFDA-approved as a breast cancer treatment rather than a fertility treatment. However, the medication is widely used safely and effectively to increase the chances of getting pregnant. As a new type of OI drug, the application of letrozole is not only limited to the clinical treatment of OI for timed intercourse but also involves many aspects of infertility treatment.

However, if you think you’re having a medical emergency, you should call 911 or your local emergency number. If you have breast cancer, your doctor might prescribe Femara for you. You should avoid any supplement containing any form of estrogen while taking letrozole.

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding. Letrozole may affect your ability to become pregnant or get a partner pregnant. Talk with your healthcare provider if you have any concerns.

The following interactions have been selected on the basis of their potential significance and steroids are not necessarily all-inclusive. Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of letrozole in the elderly. However, elderly patients are more sensitive to the effects of this medicine than younger adults. This may not be a complete list of medicines that can interact with letrozole.