Tamoxifen

Tamoxifen is an anti-estrogen drug that has antitumor properties.

Indications Tamoxifen

It is indicated for use in the treatment of estrogen-dependent breast cancer (for women, especially those who have entered menopause) or gynecomastia of the mammary glands in men. The drug can also be used in the treatment of oncological diseases of the following organs: endometrium or ovaries, as well as kidneys. And in addition to this, melanoma, sarcomas (affecting soft tissues), which occur in the presence of estrogen receptors in the tumor. The drug can be used to eliminate prostate cancer in case of resistance of the body to other drugs.

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Release form

Available in tablet form. One blister contains 10 tablets. A pack may contain 1, 3 or 10 blisters.

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Pharmacodynamics

Tamoxifen's action is based on its properties that allow it to interfere with the activity of estrogen receptors. Tamoxifen, together with individual metabolites, fights E2 for areas of connection with cytoplasmic estrogen conductors in the cells of the uterus and mammary glands, as well as the adenohypophysis and vagina. In addition, it exerts its effect in tumors containing an increased number of estrogen conductors. Unlike the estrogen conductor complex, the identical tamoxifen complex does not provoke the process of DNA synthesis inside the nucleus. Instead, it suppresses cell division, as a result of which the tumor cells begin to regress and subsequently die.

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Pharmacokinetics

After oral administration, tamoxifen is rapidly absorbed, reaching peak serum concentrations 4-7 hours after a single dose. Steady-state serum concentrations are generally reached by tamoxifen after 3-4 weeks of drug administration. It is 99% bound to plasma proteins. Metabolism, which results in the formation of breakdown products, occurs in the liver.

The active substance is excreted in 2 separate phases. The initial half-life is 7-14 hours, and the subsequent period is a slow terminal period and lasts 7 days. It is excreted mainly with feces in the form of conjugates. The remaining small part of the drug is excreted from the body with urine.

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Dosing and administration

The dose is usually prescribed individually, it depends on the indications. The daily dosage is 20-40 mg, it is recommended to take 20 mg of the drug every day for a long period of time. In case of symptoms of disease progression, the drug should be discontinued.

The tablets must be swallowed without chewing and then washed down with water. You can take the medicine in one dose in the morning, or divide the daily dosage into 2 doses and drink in the morning and evening.

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Use Tamoxifen during pregnancy

Tamoxifen is prohibited for use during pregnancy.

Contraindications

Among other contraindications:

• breastfeeding period;
• hypersensitivity to the active ingredient or other substances contained in the drug.

Caution is required when prescribing in case of diabetes mellitus, and also renal failure, eye diseases (such as cataracts), DVT, thromboembolism (including in history). In addition, in case of hypercalcemia and hyperlipidemia, thrombocyto- and leukopenia, and also in case of combination with treatment with indirect anticoagulants.

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Side effects Tamoxifen

Side effects of taking the drug include:

• Organs of the circulatory system: leukopenia or thrombocytopenia may develop (platelet levels often decrease to 80-90x10 9/l). In rare cases, pancyto- or neutropenia may occur.
• Endocrine system organs: heavy vaginal bleeding or discharge, hot flashes, menstrual irregularities, severe genital itching. Treatment with tamoxifen increases the risk of productive changes in the endometrium - endometriosis may develop, as well as polyps or hyperplasia, and in some cases even cancer. At the premenopausal stage, women may stop menstruating, and in some situations, reversible serous edema occurs in the ovaries. Men may experience loss of libido or impotence.
• Gastrointestinal organs: vomiting and nausea. In isolated cases – taste bud disorders, anorexia, diarrhea or constipation.
• Visual organs: loss of visual acuity, development of retinopathy or cataracts, corneal clouding.
• Digestive system organs: the drug can affect the lipid spectrum in the blood serum. Hypertriglyceridemia is rarely observed, in some cases with the development of pancreatitis. Treatment with tamoxifen increases the amount of liver enzymes and can sometimes cause more severe disorders (for example, cholestasis, fatty hepatosis or hepatitis).
• Reactions of the skin and its derivatives: rash, baldness or, conversely, accelerated hair growth.
• Hypersensitivity: Quincke's edema, erythema multiforme, malignant exudative erythema, parapemphigus.
• Vascular system organs: most often thrombosis is observed, and in some rare cases – pulmonary embolism.

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Interactions with other drugs

In case of combined use with cytostatics, the risk of blood clots increases.

Antacid drugs, H2 blockers, and other drugs with a similar effect increase the pH in the stomach, as a result of which the tablet dissolved in the intestine may dissolve prematurely, and thus lose its protective properties. Therefore, it is necessary to take breaks of 1-2 hours between taking such drugs and tamoxifen.

There is evidence that Tamoxifen enhances the anticoagulant effect of coumarin drugs (for example, warfarin).

Drugs that reduce the rate of calcium excretion (for example, thiazide diuretics) can, in combination with tamoxifen, increase the risk of hypercalcemia.

The combination of tamoxifen and tegafur can provoke the development of liver cirrhosis or chronic hepatitis.

When Tamoxifen is taken simultaneously with other hormonal drugs (especially contraceptives that contain estrogen), the specific effect of both drugs is weakened.

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Storage conditions

The medicine must be kept in a dry place, out of the reach of children, away from the sun. The temperature must not exceed 25° C.

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Shelf life

Tamoxifen is permitted to be used for 3 years from the date of manufacture.

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