Vitamin D3

vitamin · endocrine · digestive · renal · musculoskeletal · integumentary · immune-hematologic · Oral

Vitamin D3, a vitamin. Cholecalciferol is the pro-hormone produced from 7-dehydrocholesterol by UVB in skin. Sequentially hydroxylated (see… Oral half-life 15 d.

Cholecalciferol is the pro-hormone produced from 7-dehydrocholesterol by UVB in skin. Sequentially hydroxylated (see Vitamin D activation cascade) in liver (CYP2R1 → 25-OH-D / Calcifediol) and kidney (CYP27B1 → 1,25-(OH)₂D / Calcitriol, the active hormone). Calcitriol binds VDR to regulate ~500 genes controlling intestinal Ca²⁺ absorption, bone remodelling, and innate-immune LL-37 / CAMP expression. Magnesium is a cofactor for both hydroxylation steps.

Pharmacokinetics

• Oral — t½ 15.0 d · F 80% · ka 0.2 h⁻¹ · Vd 14 L

Related compounds

• Magnesium — synergistic
• Calcium — synergistic
• LL-37 — synergistic
• Orlistat — caution
• Calcifediol — synergistic
• Calcitriol — caution
• Vitamin D2 — synergistic
• Menaquinone-4 (MK-4) — synergistic

Sources: PMID:12499343, PMID:21118827, PMID:18326608