Effects of tibolone and raloxifene on bone mineral density in osteopenic postmenopausal women

A randomized trial was conducted in osteopenic postmenopausal women to compare the efficacy of tibolone versus raloxifene on BMD of the lumbar spine and hip. Tibolone increased lumbar spine and total hip BMD to a statistically significantly greater extent than raloxifene after two years of treatment. Introduction Both tibolone, a selective tissue estrogenic activity regulator (STEAR), and raloxifene, a selective estrogen receptor modulator (SERM), are known to prevent postmenopausal bone loss. However, no head-to-head studies to compare the efficacy on bone have been performed. Methods A double-blind, randomized trial was conducted in osteopenic postmenopausal women aged 60-79 years to compare the effects of tibolone 1.25 mg/day to raloxifene 60 mg/day on bone mineral density (BMD). Serum osteocalcin and serum type I collagen C-telopeptides were measured as biochemical markers of bone metabolism. Results Three hundred and eight subjects were allocated to treatment. Both treatments significantly increased lumbar spine BMD, however the increase was significantly larger after tibolone treatment than after raloxifene treatment (at year 1: 2.2% versus 1.2%, p <0.01 and at year 2: 3.8% versus 2.1%, p <0.001). After 2 years of treatment, the increase in total hip BMD in the tibolone group was significantly larger than in the raloxifene group (p <0.05). Both treatments significantly reduced type I collagen C-telopeptides and osteocalcin levels when compared to baseline. Conclusions Tibolone 1.25 mg/day for 2 years prevents postmenopausal bone loss in older women and results in a larger increase of BMD both at the lumbar spine and hip than raloxifene.