TIBOLONE - PREVENTION OF BONE LOSS IN LATE POSTMENOPAUSAL WOMEN

The aim of the study was to assess the effects of 2 yr of treatment wi th two dose levels of tibolone on bone mineral density and biochemical markers of bone metabolism in late postmenopause. Ninety-one healthy women, more than 10 yr after menopause, entered a 2-yr double blind, r andomized, placebo-controlled study of treatment with either 1.25 mg/d ay (n = 36) or 2.5 mg/day (n = 35) Tibolone or placebo (n = 20). Densi tometry and determinations of biochemical markers of bone metabolism i n serum and urine were performed before randomization and every 3 mont hs during the study. The results revealed a steady and equal increase in bone mineral density in both tibolone groups at the bone sites stud ied. Gains in BMD spine of 5.9 +/- 0.9% in the 1.25 mg group, 5.1 +/- 0.9% in the 2.5 mg group, and 0.4 +/- 1.1% in the placebo group were f ound. In the forearm, increases of 2.2 +/- 0.7% in the 1.25 mg group a nd 1.9 +/- 1.1% in the 2.5 mg group were detected, whereas the placebo group lost 2.1 +/- 1.0%. This was fully supported by changes in bioch emical markers of bone resorption (urinary excretion of fragments from the osteoclastic degradation of the alpha(1)-chain of the C telopepti des of type 1 collagen and hydroxyproline) and bone formation (serum o steocalcin), respectively. In conclusion, within 2 yr of treatment, ti bolone increases bone mass in the spine and prevents bone loss in the forearm in late postmenopausal women determined by densitometry and se veral biochemical parameters of bone turnover. Tibolone at two doses ( 1.25 and 2.5 mg/day) had similar effects, indicating that even lower d oses may be efficacious.