[Diagnostic imaging of treatment in osteoporosis; new active vitamin D]

Active vitamin D drugs, such as alfacalcidol or calcitriol, have been on the market for about 30 years as a remedy for osteoporosis and are still the most popular drugs for osteoporosis in Japan. Eldecalcitol (EDR), a new active vitamin D compound, became the production sale approval in 2011. The results of the randomized, active comparator, double blind study to compare its anti-fracture efficacy with alfacalcidol (ALF) concluded that EDR has superior effect to ALF in preventing vertebral fractures in osteoporotic patients. Moreover, our longitudinal analysis of hip geometry by clinical CT in a subgroup has disclosed an unexpected potential of EDR to increase the cortical cross-sectional area and to maintain cortical thickness, probably through a more potent effect of EDR in mitigating endocortical bone resorption compared to ALF.