Index of drugs

Treatment of breast cancer.

1 tabl contains 20 mg of Tamoxifen in the form of citrate.

Tamoxifen is a trans isomer of a non-steroidal triphenyl-ethylene derivative with increased anti-estrogen activity. It also exhibits agonistic activity in relation to estrogen. In humans, in the mammary gland tissues, tamoxifen has anti-estrogen activity. Depending on the age, dose and period of treatment, partial or total agonist activity was observed within some systems (eg endometrium, bone, lipid metabolism). The antiestrogen activity of tamoxifen is higher in pre-menopausal women, while in postmenopausal women, estrogenic effects in vaginal and cervical tissues. Beneficial effects of long-term treatment on the skeleton (reduction of weight loss) and cardiovascular system, as well as some of the side effects (eg increased risk of endometrial cancer) are related to the oestrogenic activity of tamoxifen. Tamoxifen binds irreversibly to the estrogen receptor, forming stable complexes. In this way, it blocks the binding of estrogen and prevents its action. At higher concentrations, tamoxifen inhibits the production of Progesterone receptors. The mechanism of anticancer effects of the drug is not fully understood. It is expected that the use of tamoxifen in postmenopausal women with advanced breast cancer will be more effective in cases of tumors with estrogen receptors (ER +, PR +) than those without these receptors (ER-, PR-). In postmenopausal women, tamoxifen reduces the total cholesterol and LDL lipoproteins by 10-20%; does not reduce bone mineral density. After oral administration, tamoxifen is rapidly absorbed from the gastrointestinal tract, reaching a maximum concentration in the blood after 4-7 h. Steady-state concentration is reached after approximately 4 weeks of treatment after multiple doses. T_0,5 is 7 days. Tamoxifen undergoes extensive metabolic changes. 2 major metabolites - N-desmethyl-tamoxifen and 4-hydroxy-tamoxifen - have anti-estrogen activity. The drug and its metabolites are excreted slowly in the form of glucuronides, mainly in the faeces.

Hypersensitivity to tamoxifen or other components of the preparation. Pregnancy and breastfeeding. Severe hepatic impairment. Patients who have ever been diagnosed with thromboembolic disease.

During tamoxifen therapy, there is an increased risk of endometrial hyperplasia and development of endometrial polyps in patients using high doses (> 30 mg) during long-term treatment (3-5 years); there was also a higher incidence of endometrial cancer in these patients. If one of the following symptoms occurs (change in the menstrual cycle, abnormal uterine bleeding or discharge from the vagina, pelvic pain, enlargement of the lymph node on the chest, swelling of the legs, unexplained dyspnea, chest pain, blurred vision), immediate implementation is recommended thorough medical examination. During treatment with tamoxifen thromboembolic events are more frequent, especially in patients receiving cytostatics at the same time. Tamoxifen should be used with extreme caution in patients with impaired hepatic function, hyperlipidemia, hyperthyroidism, cataracts, leukopenia or thrombocytopenia. Patients with lactose intolerance should be informed of the content of this sugar in tablets. Due to the lactose content, the preparation should not be used in patients with galactose intolerance, Lapp lactase deficiency or malabsorption of glucose-galactose.

The drug is contraindicated for use during pregnancy and during breastfeeding. Before starting treatment with tamoxifen in women of childbearing age, pregnancy should be ruled out. It is recommended to use contraception (non-hormonal) while using the drug.

The following may occur: decreased appetite, nausea, vomiting; liver dysfunction (slight abnormal liver enzymes), fatty liver degeneration, cholestasis,hepatitis and necrosis (drug should be discontinued in case of hepatic and biliary disorders); excessive fluid retention, less thrombosis and pulmonary embolism; headache, drowsiness, confusion; irregular menstrual cycles, uterine bleeding, pruritus vulvitis; visual disturbances, blurred vision, changes in the cornea, changes in color vision, retinal vein thrombosis, cataracts; baldness, rash; leukopenia, thrombocytopenia, anemia, rarely neutropenia and pancytopenia (also severe forms); increased triglyceride levels, pancreatitis; bone pain, hypercalcemia (in patients with bone metastases); anaphylaxis, bronchospasm, rash, angioneurotic edema, interstitial pneumonitis; climacteric symptoms (eg hot flushes, facial flushing, tachycardia, increased sweating), fatigue. In pre-menopausal women, ovarian cysts may rarely develop. There have been reports of uterine fibroids and endometrial changes (hypertrophy, polyps, increased incidence of endometrial cancer). Isolated cases of erythema multiforme and Stevens-Johnson syndrome and pemphigoid have been reported.

Treatment with the preparation may only be carried out by experienced oncologists or under their supervision.
Oral: the recommended starting dose is 20 mg per day. The use of higher doses for additional benefits, such as delayed relapse, improved survival of patients does not seem to produce the desired results. Patients with advanced breast cancer may take 30-40 mg per day. Supportive therapy usually continues for 3-5 years or until palliative therapy is implemented due to disease progression.