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

Abstract

Eldecalcitol [ED-71, 2beta-(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 microg alfacalcidol, 0.5 or 1.0 microg 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 microg increased daily urinary Ca excretion in a dose-dependent manner, and 1.0 microg eldecalcitol increased urinary Ca to a similar extent to 1.0 microg alfacalcidol. Both 0.5 and 1.0 microg eldecalcitol suppressed urinary NTX stronger than 1.0 microg alfacalcidol (-6, -30 and -35% in 1.0 microg alfacalcidol, 0.5 and 1.0 microg 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 microg alfacalcidol, 0.5 and 1.0 microg eldecalcitol-treated groups, respectively, at 12 weeks). These results demonstrate that 0.5-1.0 microg 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.