Alfacalcidol (1α-hydroxyvitamin D
3) is a prodrug of calcitriol (1α,25-dihydroxyvitamin D
3) [
C3078] which is the active form of vitamin D
3 (cholecalciferol) [
C0314]. The natural supply of vitamin D
3 in human being mainly depends on ultraviolet light for conversion of 7-dehydrocholesterol [CAS: 434-16-2] to vitamin D
3 in the skin. The transformation (hydroxylation at position 25) of vitamin D
3 is catalyzed by enzymes in the liver and the kidney to produce calcitriol. Calcitriol is active in the regulation of the absorption of calcium from the gastrointestinal tract.
However, alfacalcidol is rapidly hydroxylated to calcitriol in the liver, effectively bypassing the critical renal metabolic conversion. Therefore, alfacalcidol is effective for patients with chronic renal failure to remedy vitamin D
3 deficiency, and to increase the bone resorption and the bone formation. (The product is for research purpose only.)