[Clinical Pharmacokinetics of Active Vitamin D3 and its derivatives, and Vitamin K2(Menatetrenone).]

Active vitamin D3(calcitriol)and its derivatives(alfacalcidol, eldecalcitol), and vitamin K2(menatetrenone)are used as the therapeutic medicines for osteoporosis in Japan. Active vitamin D3 and its derivatives have their own feature of pharmacokinetics, due to differences in binding affinity for carrier protein such as vitamin D binding protein and in metabolism. Menatetrenone is easily absorbed from intestine, and distribute to bone higher than other natural vitamin K homologues.