[Frontiers in vitamin D; basic research and clinical application. Exploratory research, biological characteristic and...

In 1981 when a clinical application of alfacalcidol, a prodrug of active vitamin D, started, differentiation inducing properties of active vitamin D were found at the same year. This indicated the diversity of the physiological actions of active vitamin D, which initially had been thought only to contribute to bone and calcium metabolism. Because these physiological actions were clinically useful, the discovery revealed opportunities for the development of drugs appropriate to specific purpose by synthesizing derivatives to separate biological effects. Several active vitamin D derivatives are now commercially available and contributing to current clinical practice in the fields of psoriasis and secondary hyperparathyroidism treatments. Eldecalcitol was also joined into clinically useful derivatives as a new drug for the treatment of osteoporosis in this year. In this chapter, exploratory research, biological characteristic and pharmacokinetics including putative metabolites based on structural appearances of eldecalcitol are introduced.