Additive effects of eldecalcitol in poorly responding long-term bisphosphonate treatment for osteoporosis

We examined whether eldecalcitol (ELD) provided additive bone mineral density (BMD) and bone turnover marker gains in patients undergoing long-term bisphosphonate (BP) usage, especially in osteoporotic individuals exhibiting a poor response to BPs.

Forty-two post-menopausal patients with primary osteoporosis and low lumbar BMD (L-BMD) and/or bilateral total hip BMD (H-BMD) values receiving long-term BP treatment were prospectively enrolled. Serum bone alkaline phosphatase (BAP) was measured as a bone formation marker and urinary N-terminal telopeptide of type I collagen (NTX) was assessed as a bone resorption marker. L-BMD, H-BMD, and femoral neck BMD (N-BMD) were recorded before, at the commencement of, and during ELD administration.

BAP and urinary NTX were significantly decreased by BP therapy prior to ELD. ELD addition further significantly decreased the bone turnover markers (both p < 0.01). The mean L-BMD increase rate was 0.2% (p = 0.81) from 2 to 1 years before ELD administration, -0.7% (p = 0.30) during the year before ELD, and 2.9% (p < 0.01) during 1 year of ELD. Similar findings were observed for the mean increase rate of H-BMD, with values of 0.2% (p = 0.55), -0.7% (p < 0.01), and 1.2% (p < 0.01), respectively. The mean N-BMD increase rate was significantly increased after ELD administration (1.1%, p = 0.03) despite no gains by BP therapy alone.

This study suggests that ELD addition may be useful for osteoporotic patients exhibiting a diminished long-term BP therapy response.