ergocalciferolo

Ergocalciferolo, known in English as ergocalciferol or vitamin D2, is a fat-soluble secosteroid used to prevent and treat vitamin D deficiency. It is the plant- and fungus-derived form of vitamin D, produced from ergosterol in yeasts and mushrooms, in contrast to cholecalciferol (vitamin D3), which is animal-derived. In the body, ergocalciferolo is hydroxylated in the liver to 25-hydroxyergocalciferol (25(OH)D2) and then further hydroxylated in the kidney to the active metabolite 1,25-dihydroxyergocalciferol (1,25(OH)2D2). This metabolite binds the vitamin D receptor to regulate calcium and phosphate homeostasis, promoting intestinal absorption and bone mineralization.

Clinically, ergocalciferolo is used to correct or prevent vitamin D deficiency and related bone disorders such as rickets in children and osteomalacia or osteoporosis in adults. It is available in various oral forms and, in some settings, as injectable formulations. Dosing varies by indication, age, body weight, and baseline vitamin D status, with regimens ranging from daily lower doses to higher weekly or monthly schedules.

Pharmacokinetically, ergocalciferolo is fat-soluble, absorbed with dietary fat, and stored in body tissues. Compared with vitamin D3, ergocalciferolo generally has a shorter circulating half-life and may produce lower or differently sustained 25(OH)D levels, though both forms raise total serum 25(OH)D. Clinically relevant measurements usually report total 25(OH)D (D2 and D3 together).

Safety considerations include the risk of hypercalcemia and hypercalciuria with excessive intake. Drug interactions can affect absorption or metabolism, including bile acid sequestrants, orlistat, anticonvulsants, and glucocorticoids.