Tacalcitol is a synthetic vitamin D3 analog with high selectivity for vitamin D receptors. In pharmaceutical field, it is mainly used as active pharmaceutical ingredient (API) for topical formulations to treat psoriasis and other hyperkeratotic skin disorders. It inhibits excessive proliferation of epidermal keratinocytes and induces normal cell differentiation, alleviating skin inflammation, scaling and erythema. Compared with calcipotriol, it shows milder irritation and is suitable for application on facial and other thin skin areas. It also regulates calcium metabolism and immune responses, supporting bone health and reducing inflammatory reactions. In research, it serves as a tool compound to study vitamin D receptor signaling pathways, epidermal cell biology, and immune modulation mechanisms. It is also used in the development of novel anti-inflammatory and anti-proliferative drugs.

GHS Classification: H315 (Causes skin irritation), H319 (Causes serious eye irritation), H335 (May cause respiratory irritation). Signal Word: Warning. Acute toxicity: Oral LD50 (rat) >5000 mg/kg (low toxicity); dermal LD50 (rat) >2000 mg/kg. Skin contact may cause mild irritation, redness or dryness; eye contact may lead to transient irritation and tearing. Inhalation of dust may irritate respiratory tract, causing cough or discomfort. Chronic exposure: High doses may affect calcium homeostasis, leading to hypercalcemia or hypercalciuria; long-term topical use may cause local skin atrophy. Handling: Wear gloves, goggles and dust mask in well-ventilated area. Storage: Keep sealed, dry, away from light and heat sources. Spills: Collect with inert absorbent and dispose of as non-hazardous waste.