ObjectiveWe studied whether oral administration of ipriflavone, a synthetic derivative of naturally occurring isoflavones, could prevent bone loss occurring shortly after menopause.DesignFifty-six women with low vertebral bone density and with postmenopausal age less than five years were randomly allocated to receive either ipriflavone, 200 mg three times daily, or placebo. All subjects also received 1,000 mg elemental calcium daily.ResultsVertebral bone density declined after two years in women taking only calcium (4.9 ± 1.1%, SEM,p= 0.001), but it did not change in those receiving ipriflavone (-0.4 ± 1.1%, n.s.). A significant (p= 0.010) between-treatment difference was evidenced at both year 1 and year 2. At the end of the study, urine hydroxyproline/creatinine excretion was higher in the control group than in the ipriflavone group, as compared to no difference at baseline. Five patients taking ipriflavone and five taking placebo experienced gastrointestinal discomfort or other adverse reactions, but only one and four subjects, respectively, had to discontinue the study.ConclusionsIpriflavone prevents the rapid bone loss following early menopause. This effect is associated with a reduction of bone turnover rate.