Efficacy of combined treatment with alendronate (ALN) and eldecalcitol, a new active vitamin D analog, compared to that of concomitant ALN, vitamin D plus calcium treatment in Japanese patients with primary osteoporosis.

Combined treatment with alendronate and eldecalcitol was found to be more effective in reducing the bone turnover markers and increasing bone mineral density than alendronate treatment with vitamin D3 and calcium supplementation in the osteoporotic patients. We compared the clinical efficacy and safety of combined treatment with alendronate plus eldecalcitol (ALN + ELD) with those of treatment with ALN plus vitamin D and calcium (ALN + VitD). Osteoporotic 219 patients were randomly assigned to the ALN + ELD, or the ALN + VitD group. Primary endpoint was the inter-group differences in lumbar spine BMD (L-BMD) at patient's last visit. Secondary endpoints included the differences in BMD at other sites and the bone turnover marker (BTM) levels. L-BMD, total hip BMD and femoral neck (FN-BMD) increased from baseline by 7.30, 2.41, and 2.70 % in the ALN + ELD group, and by 6.52, 2.27, and 1.18% in the ALN + VitD group, respectively. Inter-group differences of the L-BMD and total hip BMD values were not significant. The increase of the FN-BMD was larger in the ALN + ELD group than the ALN + VitD group. Reductions of the BTMs were greater in the ALN + ELD group than the ALN + VitD group. Interaction of the percent increase of the L-BMD with the baseline values of the BTMs was observed in the ALN + VitD group only. The increases of the FN-BMD in patients with lower baseline values of type-I-collagen C-telopeptide (sCTX) and serum 25(OH) D levels <20 ng/mL were significantly larger in the ALN + ELD group than the other group. Combination treatment of ALN plus ELD was more effective in reducing the BTMs and increasing the FN-BMD than ALN treatment with vitamin D3 and calcium.