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Accession NumberDB01436
TypeSmall Molecule
GroupsApproved, Nutraceutical

Alfacalcidol is an active metabolite of Vitamin D, which performs important functions in regulation of the calcium balance and the bone metabolism. Alfacalcidol is Vitamin D-hormone analog which is activated by the enzyme 25-hydroxylase in the liver for systemic and in osteoblasts for local D-hormone actions. It possesses a unique pattern of pleiotropic effects on, e.g. gut, bone, pararthyroids, muscle and brain. Alfacalcidol is superior to plain vitamin D (cholecalciferol) because the final kidney activation of the latter is regulated by a negative feedback mechanism. (PMID:17438884,17668216)

1alpha-Hydroxy-vitamin D3
1alpha-hydroxyvitamin D3
External Identifiers Not Available
Approved Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
One Alpha Caps 0.25mcgcapsule0.25 mcgoralLeo Pharma Inc1980-12-31Not applicableCanada
One Alpha Caps 1mcgcapsule1 mcgoralLeo Pharma Inc1980-12-31Not applicableCanada
One-alphadrops2 mcgoralLeo Pharma Inc2000-12-04Not applicableCanada
One-alphacapsule0.5 mcgoralLeo Pharma IncNot applicableNot applicableCanada
One-alphaliquid2 mcgintravenousLeo Pharma Inc2001-02-20Not applicableCanada
One-alpha Sol 0.2mcg/mlliquid.2 mcgoralLeo Pharma Inc1989-12-312000-12-04Canada
Approved Generic Prescription ProductsNot Available
Approved Over the Counter ProductsNot Available
Unapproved/Other Products Not Available
International Brands
AlsiodolNot Available
One AlphaNot Available
Brand mixturesNot Available
SaltsNot Available
CategoriesNot Available
CAS number41294-56-8
WeightAverage: 400.6371
Monoisotopic: 400.334130652
Chemical FormulaC27H44O2
CC(C)CCC[C@@H](C)[C@@]1([H])CC[C@@]2([H])\C(CCC[C@]12C)=C\C=C1\C[C@@H](O)C[[email protected]](O)C1=C
DescriptionThis compound belongs to the class of organic compounds known as triterpenoids. These are terpene molecules containing 8 isoprene units.
KingdomOrganic compounds
Super ClassLipids and lipid-like molecules
ClassPrenol lipids
Sub ClassTriterpenoids
Direct ParentTriterpenoids
Alternative Parents
  • Polycyclic triterpenoid
  • Triterpenoid
  • Steroid
  • Cyclohexanol
  • Cyclic alcohol
  • Secondary alcohol
  • Hydrocarbon derivative
  • Organooxygen compound
  • Alcohol
  • Aliphatic homopolycyclic compound
Molecular FrameworkAliphatic homopolycyclic compounds
External Descriptors
IndicationAlfacalcidol is an active metabolite of Vitamin D, which performs important functions in regulation of the calcium balance and the bone metabolism.
PharmacodynamicsAlfacalcidol is Vitamin D-hormone analog which is activated by the enzyme 25-hydroxylase in the liver for systemic and in osteoblasts for local D-hormone actions.
Mechanism of actionThe first step involved in the activation of vitamin D3 is a 25-hydroxylation which is catalysed by the 25-hydroxylase in the liver and then by other enzymes. The mitochondrial sterol 27-hydroxylase catalyses the first reaction in the oxidation of the side chain of sterol intermediates. The active form of vitamin D3 (calcitriol) binds to intracellular receptors that then function as transcription factors to modulate gene expression. Like the receptors for other steroid hormones and thyroid hormones, the vitamin D receptor has hormone-binding and DNA-binding domains. The vitamin D receptor forms a complex with another intracellular receptor, the retinoid-X receptor, and that heterodimer is what binds to DNA. In most cases studied, the effect is to activate transcription, but situations are also known in which vitamin D suppresses transcription. Calcitriol increases the serum calcium concentrations by: increasing GI absorption of phosphorus and calcium, increasing osteoclastic resorption, and increasing distal renal tubular reabsorption of calcium. Calcitriol appears to promote intestinal absorption of calcium through binding to the vitamin D receptor in the mucosal cytoplasm of the intestine. Subsequently, calcium is absorbed through formation of a calcium-binding protein.
Related Articles
AbsorptionNot Available
Volume of distributionNot Available
Protein bindingNot Available
MetabolismNot Available
Route of eliminationNot Available
Half lifeNot Available
ClearanceNot Available
ToxicityHypercalcemia - Early symptoms of hypercalcemia, include nausea and vomiting, weakness, headache, somnolence, dry mouth, constipation, metallic taste, muscle pain and bone pain. Late symptoms and signs of hypercalcemia, include polyuria, polydipsia, anorexia, weight loss, nocturia, conjunctivitis, pancreatitis, photophobia, rhinorrhea, pruritis, hyperthermia, decreased libido, elevated BUN, albuminuria, hypercholesterolemia, elevated ALT (SGPT) and AST (SGOT), ectopic calcification, nephrocalcinosis, hypertension and cardiac arrhythmias.
Affected organisms
  • Humans and other mammals
PathwaysNot Available
SNP Mediated EffectsNot Available
SNP Mediated Adverse Drug ReactionsNot Available
Predicted ADMET features
Human Intestinal Absorption+0.9865
Blood Brain Barrier+0.9142
Caco-2 permeable+0.7866
P-glycoprotein substrateSubstrate0.7469
P-glycoprotein inhibitor INon-inhibitor0.5785
P-glycoprotein inhibitor IIInhibitor0.5574
Renal organic cation transporterNon-inhibitor0.7945
CYP450 2C9 substrateNon-substrate0.8188
CYP450 2D6 substrateNon-substrate0.8945
CYP450 3A4 substrateSubstrate0.7656
CYP450 1A2 substrateNon-inhibitor0.8249
CYP450 2C9 inhibitorNon-inhibitor0.8802
CYP450 2D6 inhibitorNon-inhibitor0.9434
CYP450 2C19 inhibitorNon-inhibitor0.7466
CYP450 3A4 inhibitorNon-inhibitor0.8596
CYP450 inhibitory promiscuityLow CYP Inhibitory Promiscuity0.5436
Ames testNon AMES toxic0.9077
BiodegradationNot ready biodegradable0.9944
Rat acute toxicity4.6023 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.7959
hERG inhibition (predictor II)Non-inhibitor0.8176
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397 )
ManufacturersNot Available
PackagersNot Available
Dosage forms
Capsuleoral0.25 mcg
Capsuleoral1 mcg
Capsuleoral0.5 mcg
Dropsoral2 mcg
Liquidintravenous2 mcg
Liquidoral.2 mcg
Unit descriptionCostUnit
One-Alpha 2 mcg/ml17.28USD ml
One-Alpha 2 mcg/ml Drops5.39USD ml
One-Alpha 1 mcg Capsule1.41USD capsule
One-Alpha 0.25 mcg Capsule0.47USD capsule
DrugBank does not sell nor buy drugs. Pricing information is supplied for informational purposes only.
PatentsNot Available
Experimental Properties
melting point136 °CPhysProp
Predicted Properties
Water Solubility0.00163 mg/mLALOGPS
pKa (Strongest Acidic)14.39ChemAxon
pKa (Strongest Basic)-2.8ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count2ChemAxon
Hydrogen Donor Count2ChemAxon
Polar Surface Area40.46 Å2ChemAxon
Rotatable Bond Count6ChemAxon
Refractivity124.7 m3·mol-1ChemAxon
Polarizability50.55 Å3ChemAxon
Number of Rings3ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Mass Spec (NIST)Not Available
SpectraNot Available
Synthesis ReferenceNot Available
General ReferencesNot Available
External Links
ATC CodesA11CC03M05BB06
AHFS Codes
  • 88:16.00
PDB EntriesNot Available
FDA labelNot Available
MSDSNot Available
Drug Interactions
Aluminum hydroxideThe serum concentration of Aluminum hydroxide can be increased when it is combined with Alfacalcidol.
ColesevelamThe serum concentration of Alfacalcidol can be decreased when it is combined with Colesevelam.
DanazolDanazol may increase the hypercalcemic activities of Alfacalcidol.
DigoxinAlfacalcidol may increase the arrhythmogenic activities of Digoxin.
DihydrotachysterolThe risk or severity of adverse effects can be increased when Dihydrotachysterol is combined with Alfacalcidol.
Magnesium chlorideThe serum concentration of Magnesium chloride can be increased when it is combined with Alfacalcidol.
Magnesium citrateThe serum concentration of Magnesium citrate can be increased when it is combined with Alfacalcidol.
Magnesium hydroxideThe serum concentration of Magnesium hydroxide can be increased when it is combined with Alfacalcidol.
Magnesium oxideThe serum concentration of Magnesium oxide can be increased when it is combined with Alfacalcidol.
Magnesium salicylateThe serum concentration of Magnesium salicylate can be increased when it is combined with Alfacalcidol.
Magnesium SulfateThe serum concentration of Magnesium Sulfate can be increased when it is combined with Alfacalcidol.
Mineral oilThe serum concentration of Alfacalcidol can be decreased when it is combined with Mineral oil.
OrlistatThe serum concentration of Alfacalcidol can be decreased when it is combined with Orlistat.
SucralfateThe serum concentration of Sucralfate can be increased when it is combined with Alfacalcidol.
TrichlormethiazideTrichlormethiazide may increase the hypercalcemic activities of Alfacalcidol.
Food InteractionsNot Available


Pharmacological action
General Function:
Zinc ion binding
Specific Function:
Nuclear hormone receptor. Transcription factor that mediates the action of vitamin D3 by controlling the expression of hormone sensitive genes. Recruited to promoters via its interaction with BAZ1B/WSTF which mediates the interaction with acetylated histones, an essential step for VDR-promoter association. Plays a central role in calcium homeostasis.
Gene Name:
Uniprot ID:
Molecular Weight:
48288.64 Da
  1. Reinhart GA: Vitamin D analogs: novel therapeutic agents for cardiovascular disease? Curr Opin Investig Drugs. 2004 Sep;5(9):947-51. [PubMed:15503649 ]
  2. Chen X, Ji ZL, Chen YZ: TTD: Therapeutic Target Database. Nucleic Acids Res. 2002 Jan 1;30(1):412-5. [PubMed:11752352 ]
  3. Fujishima T, Tsuji G, Tanaka C, Harayama H: Novel vitamin D receptor ligands having a carboxyl group as an anchor to arginine 274 in the ligand-binding domain. J Steroid Biochem Mol Biol. 2010 Jul;121(1-2):60-2. doi: 10.1016/j.jsbmb.2010.04.020. Epub 2010 May 6. [PubMed:20435140 ]
Pharmacological action
General Function:
Iron ion binding
Specific Function:
Catalyzes the conversion of 25-hydroxyvitamin D3 (25(OH)D) to 1-alpha,25-dihydroxyvitamin D3 (1,25(OH)2D) plays an important role in normal bone growth, calcium metabolism, and tissue differentiation.
Gene Name:
Uniprot ID:
Molecular Weight:
56503.475 Da
  1. Uchida E, Kagawa N, Sakaki T, Urushino N, Sawada N, Kamakura M, Ohta M, Kato S, Inouye K: Purification and characterization of mouse CYP27B1 overproduced by an Escherichia coli system coexpressing molecular chaperonins GroEL/ES. Biochem Biophys Res Commun. 2004 Oct 15;323(2):505-11. [PubMed:15369780 ]


Pharmacological action
General Function:
Vitamin transporter activity
Specific Function:
Involved in vitamin D transport and storage, scavenging of extracellular G-actin, enhancement of the chemotactic activity of C5 alpha for neutrophils in inflammation and macrophage activation.
Gene Name:
Uniprot ID:
Molecular Weight:
52963.025 Da
  1. Nykjaer A, Dragun D, Walther D, Vorum H, Jacobsen C, Herz J, Melsen F, Christensen EI, Willnow TE: An endocytic pathway essential for renal uptake and activation of the steroid 25-(OH) vitamin D3. Cell. 1999 Feb 19;96(4):507-15. [PubMed:10052453 ]
  2. Verboven C, Rabijns A, De Maeyer M, Van Baelen H, Bouillon R, De Ranter C: A structural basis for the unique binding features of the human vitamin D-binding protein. Nat Struct Biol. 2002 Feb;9(2):131-6. [PubMed:11799400 ]
  3. Houghton LA, Vieth R: The case against ergocalciferol (vitamin D2) as a vitamin supplement. Am J Clin Nutr. 2006 Oct;84(4):694-7. [PubMed:17023693 ]
  4. Yamamoto N, Naraparaju VR: Vitamin D3-binding protein as a precursor for macrophage activating factor in the inflammation-primed macrophage activation cascade in rats. Cell Immunol. 1996 Jun 15;170(2):161-7. [PubMed:8660814 ]
  5. Yamamoto N, Naraparaju VR: Role of vitamin D3-binding protein in activation of mouse macrophages. J Immunol. 1996 Aug 15;157(4):1744-9. [PubMed:8759764 ]
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Drug created on July 26, 2007 06:34 / Updated on August 17, 2016 12:23