[Frontiers in vitamin D; Basic research and clinical application. Effect of eldecalcitol on bone structure].

Eldecalcitol, a new active vitamin D compound, has revealed to have its superiority to alfacalcidol in preventing vertebral fractures in osteoporotic subjects, as well as in preventing major non-vertebral fracture. Several animal studies demonstrated the greater efficacy in bone metabolism comparing the traditional active vitamin D, partly in relation to improvement of trabecular bone microstructure ; increase in BV/TV, Tb.N and Tb.Th, and decrease in Tb.Sp. Furthermore, three years longitudinal observation of hip geometry and biomechanical properties using clinical CT (multi-detector row CT) has disclosed an unexpected potential of eldecalcitol to improve biomechanical parameters by the increase in cortical cross-sectional area, cortical bone mass, and cortical perimeter, and by maintaining clinical thickness, probably through a more potent effect of eldecalcitol in mitigating endocortical bone resorption compared to alfacalcidol.