Effects of ospemifene, a novel SERM, on biochemical markers of bone turnover in healthy postmenopausal women

Ospemifene is a novel selective estrogen receptor modulator (SERM). Here we studied the effects of ospemifene on bone turnover in postmenopausal women. This was a randomized, double-blind study in which 159 healthy postmenopausal women received 30 (n = 40), 60 (n = 40) or 90 mg (n = 40) of ospemifene or placebo (n = 39) for 3 months. Bone resorption was assessed by measuring the urinary outputs of N- and C-terminal crosslinking telopeptides of type I collagen (NTX and CTX, respectively). Bone formation was assessed by measuring the levels of procollagen type I N propeptide (PINP), procollagen type I C propeptide (PICP), and bone-specific alkaline phosphatase (bone ALP) in serum. All markers were studied at baseline, 3 months, and 2-4 weeks after cessation of the medication. Ospemifene decreased bone resorption dose-dependently, as seen from falls in NTX by 6.1, 9.4 and 12.9% in the 30, 60 and 90 mg ospemifene groups, respectively (p < 0.05 for all dose levels when compared to placebo). CTX values decreased in the 90 mg ospemifene group by 4.8% (p < 0.05). A dose-dependent decrease was also observed in the bone formation markers: PINP values decreased by 9.8 (p < 0.05) and 15.3% (p < 0.01), and PICP values by 12.0 and 11.9% in the 60 and 90 mg ospemifene groups, respectively. Bone ALP decreased in 60 and 90 mg ospemifene groups by 1.9 and 2.6%, respectively (p < 0.05 for both dose levels when compared to placebo). These results show that ospemifene is effective in reducing bone turnover in postmenopausal women.