Tibolone adverse effects

Tibolone is an agonist at estrogen and progestogen receptors, with weak androgenic activity. It is given as an alternative to hormone replacement therapy, without added progestogen, and has been in use for some 30 years to treat bone loss in post-menopausal women. Some long-term studies (for example over 10 years) appear to have confirmed its safety and relative freedom from adverse effects (1). In particular there is little or no increase in thrombotic events and the incidence of breast tenderness is low. 

Despite the still uncertain adverse effects profile of tibolone, it continues to be used in relieving the hot flushes caused by anti-estrogen therapy, and does so in doses that cause no additional problems. In a further double-blind, placebo-controlled study of oral tibolone 2.5 mg/day in 70 postmenopausal women taking tamoxifen after breast cancer surgery tibolone reduced the severity of hot flushes and perhaps also their incidence (3). 

In a randomized, placebo-controlled study in women who received leuprolide acetate depot 11.25 mg intramuscularly with tibolone 2.5 mg/day (n = 36), leuprolide acetate depot 11.25 mg with placebo (n = 37), or a placebo injection with placebo tablets (n = 39), irritable bowel syndrome related to the menstrual cycle improved in those who received leuprolide (5). There were hot flushes in those who took leuprolide compared with placebo no data were given about the frequency of hot flushes, but there were no withdrawals because of this symptom. Amenorrhea also occurred. Both flushing and amenorrhea are expected adverse effects of leuprolide. 

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