Letrozole is a anti-hormonal medicine used in the management of certain breast cancers in postmenopausal women. It belongs to the class of antineoplastics and immunomodulators. It acts by preventing the action of an enzyme, aromatase, responsible for the production of estrogen in postmenopausal women. Aromatase acts on androgens (androstenedione and testosterone) which it transforms into estrone and estradiol. The action of letrozole on aromatase is very specific, that is to say that this drug does not act on other levels of hormonal production. Its action on aromatase is restricted to estrogen production in peripheral tissues and the tumor itself. Its use does not require supplementation with glucocorticoids or mineralocorticoids.
Medicines containing letrozole are Femara® and its generics Letrozole marketed by laboratories Accord Healthcare, Almus, Alter, Arrow lab, Biogaran, Bluefish, Cristers, EG, Evolugen, Mylan, Sandoz, Sun, Teva, Zentiva and Zydus. These medicines are all dosed at 2.5 mg and come in the form of a box of 30 film-coated tablets.
Letrozole is indicated in the treatment of early invasive breast cancer in postmenopausal women with positive hormone receptors, as an extension of treatment for invasive hormone-dependent breast cancer in postmenopausal women who have received treatment with tamoxifen for 5 years, in first-line treatment of hormone-dependent breast cancer at an advanced stage in postmenopausal women, in treatment of breast cancer at an advanced stage after relapse or progression of the disease in postmenopausal women (natural or artificial menopause) who have been treated with antiestrogens, and in treatment of postmenopausal women with hormone receptor positive with HER-2 negative breast cancer when chemotherapy is not adequate and immediate surgery is not indicated. Letrozole is not a suitable treatment for women with hormone receptor negative breast cancer. It is also not indicated to treat male breast cancers.
The action of letrozole has an impact on fertility and could increase it. This drug acts by decreasing the synthesis of estrogens by inhibiting aromatase. In premenopausal women, inhibition of estrogen synthesis leads to increased levels of LH and FSH. However, the increase in FSH levels stimulates follicle growth and can thus induce ovulation.. Letrozole is at risk of reproductive toxicity, isolated cases of congenital anomalies having been observed. DSerious birth defects may occur if taken during pregnancy. Thus, letrozole should not be used in women whose menopause is not clearly confirmed. In rare cases, ovarian function may return to activity with letrozole treatment, despite a proven menopause before treatment. Effective contraception should be considered with the doctor as a precaution.
Letrozole is a drug belonging to the list I of poisonous substances. A prescription is required to be able to get it in pharmacies.
The most common side effects with letrozole are hot flashes, digestive disorders (constipation or diarrhoea, abdominal pain, nausea, vomiting), high cholesterol, bone, muscle and joint pain, fatigue, excessive sweating, change in appetite, weight gain, depression, hair loss, rash, dry skin, vaginal bleeding, swelling, chest pain, headache and dizziness. Other important side effects that may occur are skeletal effects such as osteoporosis and/or bone fractures, as well as cardiovascular events (including hypertension, palpitations, strokes and thromboembolic events). Other effects may occur but they are much rarer (urinary tract infections, tumor pain, leucopenia, anxiety, irritability, drowsiness, insomnia, memory problems, changes in taste and sensations, vision problems, difficulty breathing, cough, dry mouth, stomatitis, liver problems, itching, hives, potentially serious skin conditions, tendinitis and tendon ruptures, frequent urination, vaginal dryness and discharge, breast pain, generalized oedema, thirst, fever, dry mucous membranes and weight loss).
There are some contraindications to Letrozole such as hypersensitivity to one of the components of the drug, pre-menopause, pregnancy and lactation. People with a galactose intolerance, total lactase deficiency or glucose-galactose malabsorption syndrome should not take this medicine. When menopause is not certain, a determination of LH, FSH and/or estradiol should be carried out before initiating treatment with letrozole. Monitoring is required in women with hepatic impairment. In the event of a history of bone fractures or osteoporosis, an assessment of bone mineral density should be made before starting treatment with letrozole, due to the reduction in estrogen levels that this treatment causes. Monitoring should also be ensured during and after treatment. In the event of a tendon injury, appropriate measures must be put in place, letrozole can in rare cases cause lesions or rupture of tendons.
Letrozole is not a photosensitizing drug, that is, it is not particularly problematic with sun exposure. However, due to the skin disorders it can cause, as well as due to the weakening of the skin due to cancer and other possible treatments, sun exposure is not recommended. It is advisable to protect yourself with protective clothing, a hat, sunglasses and sunscreen with an index greater than or equal to 50.
Letrozole does not interact particularly with alcohol. Nevertheless, taking alcohol is not recommended in the event of an ongoing pathology and particularly in the event of cancer, as this could delay healing. In addition, alcohol can accentuate certain undesirable effects of letrozole such as osteoporosis and bone risks, digestive disorders, hot flushes or liver disorders (especially in the event of excessive consumption). It is therefore strongly advised not to consume alcohol while taking letrozole, and generally throughout the treatment of breast cancer.
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