Tamoxifen – a non-steroidal anti-estrogen agent. It inhibits the action of endogenous estrogens by competitive binding to estrogen receptors. In some cases, effective in estrogennezavisimyh tumors, indicating that there are other mechanisms of action of tamoxifen. Tamoxifen has partial estrogenic action on the endometrium e.g., bone and serum lipid.
After oral administration, rapidly absorbed, the maximum serum concentration is achieved within 4-7 hours after ingestion. Stable concentration (about 300 ng / L) is set after 4 weeks of treatment at a dose of 40 mg / day. Almost 99% of tamoxifen binds to serum albumin. Metabolism performed by hydroxylation, demethylation and conjugation, resulting in a number of metabolites that are identical with the starting material pharmacological profile. Excretion is carried out mainly in the feces; half-life main circulating metabolite in blood is 14 days.
Substances characteristic of Tamoxifen
The antitumor agent (antiestrogen). Tamoxifen citrate – a white crystalline powder and odorless. Very slightly soluble in water (1: 5000), it is easy – in hot water (1: 2), soluble in ethanol, methanol, acetone. Hygroscopic high humidity, is sensitive to ultraviolet. The molecular weight of 563.65.
Ossalgia, pain in the lesions, fever; loss of appetite, nausea, vomiting, constipation or diarrhea, in rare cases – fatty liver, cholestasis, hepatitis; flushing of the skin with a sensation of heat; leukopenia, thrombocytopenia, thrombosis, thromboembolism, thrombophlebitis ; skin rash, skin dryness, increase in the size of soft tissue structures, sometimes accompanied by severe erythema affected areas and adjacent areas (usually resolves within 2 weeks); hypercalcemia, peripheral edema (fluid retention associated with), alopecia, increased body weight; depression, headache , dizziness , myasthenia gravis , fatigue, drowsiness, confusion; loss of visual acuity, corneal opacities, cataracts , retinopathy , optic neuritis .
Treatment: symptomatic. No specific antidote.