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Health

Letrozole

, medical expert
Last reviewed: 04.07.2025
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Letrozole is an anticancer drug that works by blocking the binding of estrogens.

The drug also has an anti-estrogenic effect, selectively slowing down the activity of aromatase (an important bioenzyme in the processes of estrogen binding) by highly specific synthesis with components of the said enzyme. At the same time, the drug slows down the implementation of estrogen biosynthesis in healthy peripheral tissues, as well as neoplastic tissues. [ 1 ]

Indications Letrozole

It is used in women during postmenopause - in the early stages of malignant neoplasms in the breast area (expressing endings of female sex hormones), as an additional treatment.

It is used in early-stage malignant breast lesions, during postmenopause after completion of standard additional therapy with tamoxifen – as a prolonged additional substance.

Prescribed for hormone-dependent malignant breast lesions (of widespread nature) in postmenopause – first-line therapy.

It is also used in cases of malignant breast carcinoma of a widespread nature in postmenopausal women who have previously used antiestrogens.

Release form

The substance is released in tablets - 10 pieces in a cell pack; in a box - 3 such packs.

Pharmacodynamics

During postmenopause, estrogens in women are formed mainly with the help of aromatase, which partially converts androgens formed inside the adrenal glands into estrone and estradiol.

Continuous use of the drug in a daily dose of 0.1-5 mg causes a decrease in plasma values of estradiol and estrone with estrone sulfate to a level of up to 95% of the initial values. Inhibition of estrogen binding should be maintained throughout the entire period of therapy. [ 2 ]

When estrogen binding is blocked, levels of androgens, which are chemically precursors to estrogens, increase.

However, Letrozole therapy slightly increases the risk of developing osteoporosis.

Adjuvant treatment in early stages of malignant breast carcinoma reduces the likelihood of recurrence, increases 5-year survival without symptoms of progression, and reduces the risk of developing metastases and secondary neoplasms.

Prolonged adjuvant treatment reduces the likelihood of relapse by 42%.

Pharmacokinetics

When taken orally, the medication is absorbed in the intestine at a high rate and almost completely. The average bioavailability is 99.9%. Eating food reduces the absorption rate. To achieve Cmax, it takes an average of 1 hour if the drug is taken on an empty stomach or 2 hours if taken with food.

Intraplasmic protein synthesis is approximately 60%. With prolonged use of the drug, its accumulation is not observed.

Most of the drug is involved in metabolic processes with the formation of a metabolic component that does not have activity.

Excretion is mainly realized in the form of metabolic elements together with urine; a smaller part is excreted in the intestine. The half-life is 2 days.

Dosing and administration

The medication is taken orally, without reference to food intake. 2.5 mg of the medication is taken once a day. The drug is used daily and for a long time (5 years or until a relapse occurs).

Prolonged adjuvant treatment usually lasts 4 years (maximum 5 years). If symptoms of carcinoma progression are detected, the use of the drug should be completely discontinued.

In people with carcinoma in the last stage or with manifestations of metastasis, therapy is continued until significant development of the neoplasm is observed.

  • Application for children

The medicine is not intended for use in pediatrics.

Use Letrozole during pregnancy

Letrozole should not be used during breastfeeding or pregnancy.

Contraindications

Main contraindications:

  • hormonal status that is observed during fertility;
  • severe intolerance to the components of the drug.

Caution is required when used in individuals with glucose-galactose malabsorption, lactose intolerance and lactase deficiency.

Side effects Letrozole

Side effects include:

  • lesions associated with the nervous system: drowsiness, dysesthesia, dizziness, paresthesia, depression and nervousness, as well as insomnia, anxiety, hypoesthesia, irritability, temporary disorders of cerebral blood flow and memory impairment;
  • problems affecting the digestive tract: nausea, pain in the abdominal area, constipation, dyspepsia, dry mouth, vomiting, stomatitis and diarrhea, as well as increased activity of intrahepatic enzymes;
  • disorders of hematopoietic processes: leukopenia;
  • respiratory disorders: cough or dyspnea;
  • signs associated with blood flow: arterial thrombosis, tachycardia, stroke, thrombophlebitis affecting superficial and deep veins, pulmonary embolism, increased blood pressure, as well as coronary heart disease;
  • epidermal lesions: rashes, Quincke's edema, dry skin, hyperhidrosis, itching, alopecia, anaphylactic symptoms and urticaria;
  • disorders affecting the functioning of the musculoskeletal system: myalgia, arthritis, fractures, arthralgia, as well as osteoporosis and pain affecting the bones;
  • problems related to the senses: cataracts, taste disorders and blurred vision;
  • disorders affecting urogenital function: bleeding, pain affecting the sternum, increased frequency of urination, vaginal discharge and infections;
  • metabolic disorders: anorexia, thirst, weight gain or loss, increased appetite and hypercholesterolemia;
  • other manifestations: fatigue, malaise, peripheral edema, paroxysmal feeling of heat, hyperthermia, asthenia, generalized edema, dry mucous membranes and pain in the area of neoplasm foci.

Overdose

There are data on Letrozole intoxication.

There are no specific treatments for poisoning with this drug, so symptomatic and supportive measures are taken. The drug can be excreted from the body through hemodialysis.

Storage conditions

Letrozole should be stored in a place protected from moisture, children and sunlight. The temperature level should not exceed 25 °C.

Shelf life

Letrozole is approved for use within a 24-month period from the date of manufacture of the therapeutic substance.

Analogues

Analogues of the drug are Femara, Aralet, Letromara and Lerza with Letrotera and Letrozole Teva, and also Etrusil.

Reviews

Letrozole receives few reviews from patients – people with cancer are not very willing to talk about the course of their pathology and therapy.

Oncologists consider medications from this category to be very effective (which is confirmed by scientific research and testing) in the treatment of breast carcinoma.

Attention!

To simplify the perception of information, this instruction for use of the drug "Letrozole" translated and presented in a special form on the basis of the official instructions for medical use of the drug. Before use read the annotation that came directly to medicines.

Description provided for informational purposes and is not a guide to self-healing. The need for this drug, the purpose of the treatment regimen, methods and dose of the drug is determined solely by the attending physician. Self-medication is dangerous for your health.

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