Mechanism of action The efficacy of<unk>  in the treatment of psoriasis was first noticed by the observation of patients receiving various forms of vitamin D in an osteoporosis study. Unexpectedly, some patients who also suffered from psoriasis experienced dramatic reductions in lesion counts. The precise mechanism of<unk>  in remitting psoriasis is not well understood. However, it has been shown to have comparable affinity with calcitriol for the vitamin D receptor (VDR), while being less than 1% as active as the calcitriol in regulating calcium metabolism. The vitamin D receptor belongs to the steroid/thyroid receptor superfamily, and is found on the cells of many different tissues including the thyroid, bone, kidney, and T cells of the immune system. T cells are known to play a role in psoriasis, and it is thought that the binding of<unk>  to the VDR modulates the T cells gene transcription of cell differentiation and proliferation related genes. In mouse studies, topical<unk>  administration to the ear and dorsal skin led to a dose-dependent increase in the production of the epithelial cell-derived cytokine TSLP by keratinocytes, and triggered atopic dermatitis at high concentrations. This upregulation of TSLP production due to<unk>  application is thought to be mediated through the coactivation of vitamin D receptor/RXRα and vitamin D receptor/RXRβ heterodimers. As psoriasis is typically thought to be partially driven by Th1/Th17 inflammatory cytokines,<unk>  treatment at appropriate concentrations may alleviate psoriasis symptoms by repressing Th1/Th17 inflammation through TSLP production, which is linked to a Th2 response. However, it is important to note that this has not yet been confirmed. Pharmacokinetics After application and systemic uptake,<unk>  undergoes rapid hepatic metabolism.<unk>  is metabolized to MC1046 (the α,β−unsaturated ketone analog), which is subsequently metabolized to its primary metabolite, the saturated ketone analog MC1080. MC1080 is then slowly metabolized to calcitroic acid. The metabolites of<unk>  are less potent than the parent compound.
Calcipotriol
Estriol succinate
Estriol 
Estriol
Tazarotene
Methandriol
Fluocinonide
Trifarotene