Ergocalciferol
Vitamin D2, a chemical compound
Ergocalciferol, also known as vitamin D2 and nonspecifically calciferol, is a type of vitamin D found in food. It is used as a dietary supplement to prevent and treat vitamin D deficiency due to poor absorption by the intestines or liver disease. It may also be used for low blood calcium due to hypoparathyroidism. It is taken by mouth or via injection into a muscle.
Excessive doses can result in vitamin D toxicity causing increased urine production, high blood pressure, kidney stones, kidney failure, muscle weakness, and constipation. If high doses are taken for a long period of time, tissue calcification may occur. Normal doses are safe in pregnancy. It works by increasing the amount of calcium absorbed by the intestines and reabsorbed by the kidneys. Food in which it is found include some mushrooms.
Ergocalciferol was first described in 1936. Ergocalciferol is available as a generic medication and over the counter. In 2023, it was the 48th most commonly prescribed medication in the United States, with more than 13 million prescriptions. Certain foods such as breakfast cereal and margarine have ergocalciferol added to them in some countries. It is on the World Health Organization's List of Essential Medicines.
01Use
Ergocalciferol may be used as a vitamin D supplement, whereas cholecalciferol (vitamin D3) is produced naturally by the skin when exposed to ultraviolet light. Ergocalciferol (D2) and cholecalciferol (D3) are considered to be equivalent for vitamin D production, as both forms appear to have similar efficacy in ameliorating rickets and reducing the incidence of falls in elderly patients. Conflicting reports exist, however, concerning the relative effectiveness, with some studies suggesting that ergocalciferol has less efficacy based on limitations in absorption, binding, and inactivation. A meta-analysis concluded that evidence usually favors cholecalciferol in raising vitamin D levels in blood, although it stated more research is needed.
02Mechanism
Ergocalciferol is a secosteroid formed by a photochemical bond breaking of a steroid, specifically, by the action of ultraviolet light (UV-B or UV-C) on ergosterol, a form of provitamin D2.
Like cholecalciferol, ergocalciferol is inactive by itself. It requires two hydroxylations to become active: the first in the liver by CYP2R1 to form 25-hydroxyergocalciferol (ercalcidiol or 25-OH D2), and the second in the kidney by CYP27B1, to form the active 1,25-dihydroxyergocalciferol (ercalcitriol or 1,25-(OH)2D2), which activates the vitamin D receptor. Unlike cholecalciferol, 25-hydroxylation is not performed by CYP27A1 for ergocalciferol.
Ergocalciferol and metabolites have lower affinity to the vitamin D-binding protein compared to the D3 counterparts. The binding affinity of ercalcitriol to the vitamin D receptor is similar to that of calcitriol. Ergocalciferol itself and metabolites can be deactivated by 24-hydroxylation.
03Names
Viosterol, the name given to early preparations of irradiated ergosterol, is essentially synonymous with ergocalciferol. However, currently, Viosterol is also the brand name for cholecalciferol (vitamin D3) in some countries.
Ergocalciferol is manufactured and sold under various brand names, including Deltalin (Eli Lilly and Company), Drisdol (Sanofi-Synthelabo), and Calcidol (Patrin Pharma).
Sources and credits
This article is adapted from the Wikipedia article “Ergocalciferol”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Ergocalciferol.svg by Calvero, Public domain
- Vitamin D pills.jpg by Mx. Granger, CC0
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