[Postmenopausal metabolic effects of a synthetic estrogen (tibolone) with a characteristic estrogenic action]

Life expectancy in women has nearly reached 80 yr old, therefore the postmenopausal period is considered very important, particularly regarding the benefits of hormone replacement therapy. At the present there are several therapeutic options in order to protect against the long term complications resulting from chronic hypoestrogenism and avoiding some of the side effects associated with estrogens medication, tibolone is a synthetic steroid possessing mild estrogenic effect and some progestagenic and androgenic actions; moreover this steroid does not require to be converted to estradiol. We studied the effect of administering tibolone 2.5 mg daily orally during six months to 11 postmenopausal women in order to analyze any changes on several biochemical markers. Estradiol concentrations were not modified although FSH, total cholesterol, low density lipoproteins and triglycerides levels decreased. Collaterally there was observed an increment in high density lipoproteins and sexual hormone binding globulin. It is concluded that tibolone exerts its effect directly on specific receptor tissues without being converted to estradiol so that this finding may help to understand some of the clinical effects, particularly upon mammary gland, endometrium and body weight.