Calcifediol-D6 is the deuterated form of Calcifediol, which is a prehormone that is produced in the liver by hydroxylation of vitamin D3 by the enzyme cholecalciferol 25-hydroxylase.
Calcitriol D6 is the deuterated form of Calcitriol, which is the hormonally active form of vitamin D. Calcitriol is the active metabolite of vitamin D3 that activates the vitamin D receptor.