Colecalciferol (Vitamin D3)

Colecalciferol (Vitamin D3)


Colecalciferol, also known as vitamin D3 and cholecalciferol, is a type of vitamin D that is normally produced by the skin when exposed to sunlight; it is also found in some foods and can be taken as a dietary supplement. It is used to treat and prevent vitamin D deficiency and related diseases, including rickets (primarily children). It is also used for familial hypophosphatemia, hypoparathyroidism, which causes low blood calcium levels, and Fanconi syndrome. Vitamin D supplements may not be effective in people with severe kidney disease. It is usually taken by mouth in the form of drops. Vitamin D3 is available as an OTC ("over the counter") product without a prescription.



Colecalciferol alone is inactive and must first be activated in the liver. All of its metabolites are bound to vitamin D-binding protein in the blood. The action of calcitriol is mediated by the vitamin D receptor, a nuclear receptor that regulates the synthesis of hundreds of proteins and is present in virtually every cell in the body.


Colecalciferol is readily absorbed from the small intestine in the presence of fat absorption defects. Protein binding for colecalciferol is 50 to 80%. Specifically, vitamin D3 (from food or skin) is bound in plasma to vitamin D-binding protein (DBP) formed in the liver. In the liver, colecalciferol is hydroxylated to calcidiol (25-hydroxycholecalciferol) by the enzyme vitamin D 25-hydroxylase. In the kidney, calcidiol then serves as a substrate for 1-alpha-hydroxylase, resulting in calcitriol (1,25-dihydroxycholecalciferol), the biologically active form of vitamin D3. Degradation occurs via the enzyme 24-hydroxylase and excretion occurs entirely through the intestine.


Since it is a naturally occurring vitamin, no interactions are to be expected.


Side effects

Side effects are not expected with normal use. In case of very strong overdose ostheoporosis may occur. Furthermore, calcium deposits in kidneys and other organs may occur, which may irreversibly impair their function.

Chemical & physical properties

ATC Code A11CC05
Formula C27H44O
Molar Mass (g·mol−1) 384,64
Physical State solid
Melting Point (°C) 84–85
CAS Number 67-97-0
PUB Number 5280795
Drugbank ID DB00169

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All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.
Markus Falkenstätter, BSc

Markus Falkenstätter, BSc

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Mag. pharm. Stefanie Lehenauer

Mag. pharm. Stefanie Lehenauer

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

The content of this page is an automated and high-quality translation from DeepL. You can find the original content in German here.


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