alfacalcidol alfacalcidol alfacalcidol (or 1-hydroxycholecalciferol) is an analogue of vitamin d used for supplementation in humans and as a poultry feed additive. alfacalcidol names preferred iupac name (1r,3s,5z)-4-methylidene-5-octahydro-4h-inden-4-ylidene}ethylidene]cyclohexane-1,3-diol other names alphacalcidol; 1-hydroxycholecalciferol identifiers cas number 41294-56-8 y 3d model (jsmol) interactive image chebi chebi:31186 n chembl chembl32540 n chemspider 4445376 y drugbank db01436 y echa infocard 100.050.253 kegg d01518 y pubchem cid 5282181 unii urq2517572 y comptox dashboard (epa) dtxsid0022569 inchi inchi=1s/c27h44o2/c1-18(2)8-6-9-19(3)24-13-14-25-21(10-7-15-27(24,25)5)11-12-22-16-23(28)17-26(29)20(22)4/h11-12,18-19,23-26,28-29h,4,6-10,13-17h2,1-3,5h3/b21-11+,22-12-/t19-,23-,24-,25+,26+,27-/m1/s1 ykey: ofhcowsqambjiw-avjtysnksa-n yinchi=1/c27h44o2/c1-18(2)8-6-9-19(3)24-13-14-25-21(10-7-15-27(24,25)5)11-12-22-16-23(28)17-26(29)20(22)4/h11-12,18-19,23-26,28-29h,4,6-10,13-17h2,1-3,5h3/b21-11+,22-12-/t19-,23-,24-,25+,26+,27-/m1/s1key: ofhcowsqambjiw-avjtysnkbm smiles o1cc(\c(=c)(o)c1)=c\c=c2/ccc3(2cc3(c)cccc(c)c)c properties chemical formula c27h44o2 molar mass 400.64 g/mol melting point 136 °c (277 °f; 409 k) solubility in water 0.016 g/100 ml pharmacology atc code a11cc03 (who) license data eu ema: by inn legal status uk: pom (prescription only) eu: rx-only except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references alfacalcidol has a weaker impact on calcium metabolism and parathyroid hormone levels than calcitriol, however alfacalcidol has significant effects on the immune system, including regulatory t cells. it is considered to be a more useful form of vitamin d supplementation, mostly due to much longer half-life and lower kidney load. it is the most commonly prescribed vitamin d metabolite for patients with end stage renal disease, given that impaired renal function alters the ability to carry out the second hydroxylation step required for the formation of the physiologically active form of vitamin d, 1,25-dihydroxyvitamin d3. alfacalcidol is an active vitamin d3 metabolite, and therefore does not require the second hydroxylation step in the kidney. it was patented in 1971 and approved for medical use in 1978. trade names pharmaceutical trade names include alphad and one-alpha. other animals used as a poultry feed additive, it prevents tibial dyschondroplasia and increases phytate bioavailability.