Tibolone - an alternative to estrogen substitution

Tibolone is a synthetic steroid hormone with various tissue-specific estrog enic, progestogenic, and androgenic effects. Symptoms of menopause are trea ted effectively by both tibolone and estrogens and even better by tibolone with respect to mood and libido. Vaginal dryness is relieved due to its est rogenic effect on the vaginal mucosa. Endometrium and myometrium are not stimulated by tibolone. No cyclic bleedi ng occurs and the incidence of bleeding disorders is markedly reduced as co mpared to estrogens. In breast cancer cells endogenous estrogen production in vitro is dramatica lly decreased by low concentrations of tibolone, and in animals growth of e xperimental breast carcinomas is markedly inhibited by tibolone, comparable to the effect of antiestrogens. Clinically,the incidence of breast tendern ess is reduced and, compared to estrogens, there is a marked decrease in br east density on mammogrphy. Bone preservation can be achieved with tibolone as effectively as with estr ogens. Concentrations of total cholesterol, triglicerides, and lipoprotein as risk factors for cardiovascular disease are decreased by tibolone, where as levels of HDL cholesterol are increased. In animals,the formation of art eriosclerotic plaques can be significantly reduced by tibolone. No definite conclusions can currently be drawn concerning the prevention of cardiovasc ular disease in women. In summary,the clinical profile of tibolone for postmenopausal hormone repl acement therapy seems to be close to "ideal". Estrogen effects on complaint s related to menopause, vagina, and bone are achieved equally effectively. Proliferation of endometrial and myometrial tissue can be avoided. Cyclic b leeding does not occur and bleeding disorders are significantly reduced. lf prospective trials can demonstrate a protective effect concerning breast c ancer and cardiovascular disease,tibolone will be a highly at tractive alte rnative to estrogens. However, currently estrogen replacement therapy (incl uding progestins) is the "gold standard" of postmenopausal hormone replacem ent therapy.