[Tibolone]

Abstract

INDIRECT MECHANISM OF ACTION: Tibolone (OD 14) is the precursor of its active principles that are its metabolites: 3 alpha and 3 beta hydroxylated derivatives. In vivo, the latter behave like estrogens. Certain tissues (liver, endometrium) may metabolize the 3 beta ol derivative into the delta 4 isomer with progestagenic and androgenic activity. The metabolism of the product in other tissues such as the breast and brain is unknown.

Activity: At the dose of 2.5 mg/day, the product expresses an estrogen activity equivalent to that observed with classical doses of estrogens in the brain, genito-urinary tract, vascular endothelium and bone. In the brain and muscle, it also has a slightly androgenic effect and in the breast an antiestrogenic effect. ON METABOLIC LEVEL: The product acts like a minor androgen (lowering triglycerides and HDL cholesterol without interfering in the cholesterol cell flow) and it stimulates fibrinolysis. ON CLINICAL LEVEL: Tibolone treats the symptoms of estrogen privation and protects against bone loss, without inducing bleeding or mastodynia. There is a lack of large epidemiological studies on prevention of fracture risks, cardiovascular effects and breast. Tolerance in the population studied was excellent (healthy population). However, tolerance remains to be assessed in particular sub-groups (populations at risk of certains pathologies).