(1R,3S)-5-[2-[(1R,3aR,7aS)-1-[(2R,5S)-5-hydroxy-6-methyl-heptan-2-yl]-7a-methyl-2,3,3a,5,6,7-hexahydro-1H-inden-4-ylidene]ethylidene]-4-methylidene-cyclohexane-1,3-diol

Vitamin D aids in the absorption of calcium and has central roles in bone formation and maintenance, hypertension, cancer, and immunity. In addition, the active form of vitamin D, 1,25-dihydroxy vitamin D₃, decreases the proliferation and increases differentiation of keratinocytes. 1,24-dihydroxy Vitamin D₃ is an analog of 1,25-dihydroxy vitamin D₃ which, when used in a 4 μg/g ointment, safely and effectively suppresses psoriasis. It also is effective at increasing the time interval between phototherapy cycles when ultraviolet light is used for psoriasis. 1,24-dihydroxy Vitamin D₃ inhibits the growth of both normal and psoriatic human keratinocytes (IC₅₀ ~ 10 nM) via the vitamin D receptor. It also suppresses the production of RANTES and IL-8 by human dermal fibroblasts and reduces cutaneous lymphocyte-associated antigen on CD4⁺ T cells, impairing migration and skin infiltration.

Tacalcitol Monohydrate is used as a vitamin D analog used in combination with Imatinib (G407000) in the therapy of non-small cell lung cancer. It is a COVID19-related research product.