Comparison of the effects of eldecalcitol and alfacalcidol on bone and calcium metabolism

Eldecalcitol [ED-71, 2β-(3-hydroxypropyloxy)-1,25-dihydroxyvitamin D3] increases lumbar and hip bone mineral density (BMD) in a dose-dependent manner in osteoporotic patients with vitamin D supplementation. However, there has been no head-to-head comparison of the effects of eldecalcitol with alfacalcidol on bone and calcium metabolism in human subjects. Therefore, a randomized open-label clinical trial was conducted to compare the effect of eldecalcitol on bone turnover markers and calcium metabolism in 59 Japanese postmenopausal women. Subjects were randomly assigned to receive 1.0 μg alfacalcidol, 0.5 or 1.0 μg eldecalcitol once a day for 12 weeks. There was almost no increase in serum calcium (Ca) throughout the study period. Eldecalcitol from 0.5 to 1.0 μg increased daily urinary Ca excretion in a dose-dependent manner, and 1.0 μg eldecalcitol increased urinary Ca to a similar extent to 1.0 μg alfacalcidol. Both 0.5 and 1.0 μg eldecalcitol suppressed urinary NTX stronger than 1.0 μg alfacalcidol (−6, −30 and −35% in 1.0 μg alfacalcidol, 0.5 and 1.0 μg eldecalcitol-treated groups, respectively, at 12 weeks). In contrast, changes in serum BALP were similar among the three groups (−22, −22 and −29% in 1.0 μg alfacalcidol, 0.5 and 1.0 μg eldecalcitol-treated groups, respectively, at 12 weeks). These results demonstrate that 0.5–1.0 μg eldecalcitol can effectively inhibit bone resorption stronger than alfacalcidol with a similar effect on bone formation and a comparable effect on urinary Ca excretion, and suggest that eldecalcitol may have a better osteoprotective effect than alfacalcidol.