Prevention of early postmenopausal bone loss using low doses of conjugated estrogens and the non-hormonal, bone-active drug ipriflavone

Hormone replacement therapy is the optimal therapeutic choice for postmenopausal syndrome. While low doses of estrogens (0.3 mg/day of conjugated estrogens) can counteract neurovegetative menopausal symptoms, higher doses (0.625 mg/day of conjugated estrogens) are required to prevent bone loss in postmenopausal women. Experimental and clinical studies have shown that ipriflavone, a non-hormonal isoflavone derivative, is effective in the prevention and treatment of postmenopausal osteoporosis. The aim of the present investigation was to evaluate the efficacy and tolerability of ipriflavone and very low doses of equine conjugated estrogens on bone loss in early postmenopausal women. Eighty-three healthy postmenopausal women (50.3 +/- 0.7 years) were enrolled for this 1-year multicenter study. All subjects were randomly allocated to receive: double placebo (n = 24; group A), placebo plus conjugated equine estrogens 0.30 mg/day (n = 31; group B) or conjugated equine estrogens 0.30 mg/day plus oral ipriflavone 200 mg tris in die at meals (n = 28; group C), according to a double-masked design. Among women who completed the treatment period (valid completers), those of group A showed a progressive decrease in forearm bone density (FBD; measured by dual photon absorptiometry) that reached 1.7% after 12 months. The women in group B maintained their FBD in the first 6 months of treatment but, at the end of the study, showed a bone loss of 1.4% compared with basal values. By contrast, women in group C showed a significant increase in FBD after 1 year of treatment (+5.6%; p < 0.01). Both valid completers and intention to treat analyses revealed a significant difference (p < 0.05) between group A and group C over the study period. None of the treatments produced significant changes of biochemical markers of bone turnover, while hot flushes and other climacteric symptoms were significantly reduced after the sixth month of treatment in women receiving estrogens. Adverse events were generally mild, and did not differ among the groups. The results of this study suggest that low doses of estrogens combined with ipriflavone could represent a new therapeutic approach to the treatment of the postmenopausal syndrome.