Doxercalciferol (other name: 1α-hydroxyvitamin D₂), a synthetic vitamin D₂ analog, was first synthesized from ergosterol [E0018].¹⁾ It is a prodrug requiring hepatic metabolism to the active metabolite 1α,25-dihydroxyvitamin D₂ (1α, 25-(OH)₂D₂), a biologically active form of vitamin D₂.²⁾ The active vitamin D₂ binds the vitamin D receptor (VDR) to result in the selective activation of vitamin D responsive pathway. It has been reported that doxercalciferol reduces parathyroid hormone (PTH) levels by inhibiting PTH synthesis and secretion.³⁾ In clinical, doxercalciferol is used for the treatment of secondary hyperparathyroidism (2HPT) and metabolic bone disease.^3,4) (The product is for research purpose only.)