Secosteroids

Cholecalciferol, also known as vitamin D3, colecalciferol or calciol, is a skin-made vitamin D that is found in certain foods and used as a dietary supplement. It was first described in 1936, and is on the World Health Organization's List of Essential Medicines. In 2023, it was the 68th most commonly prescribed medication in the United States, with more than 9million prescriptions, and is available as a generic medication.

Calcitriol is a hormone and the active form of vitamin D, normally made in the kidney. It is also known as 1,25-dihydroxycholecalciferol. It binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes. Calcitriol increases blood calcium mainly by increasing the uptake of calcium from the intestines.

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.

Calcipotriol, also known as calcipotriene and sold under the brand name Dovonex among others, is a synthetic derivative of calcitriol, a form of vitamin D. It is used in the treatment of psoriasis.

Calcifediol, also known as calcidiol, 25-hydroxycholecalciferol, or 25-hydroxyvitamin D3 (abbreviated 25(OH)D3), is a form of vitamin D produced in the liver by hydroxylation of vitamin D3 (cholecalciferol) by the enzyme vitamin D 25-hydroxylase. Calcifediol can be further hydroxylated by the enzyme 25(OH)D-1α-hydroxylase, primarily in the kidney, to form calcitriol (1,25-(OH)2D3), which is the active hormonal form of vitamin D.

Alfacalcidol (or 1-hydroxycholecalciferol) is an analogue of vitamin D used for supplementation in humans and as a poultry feed additive.

Tacalcitol (1,24-dihydroxyvitamin D3) is a synthetic vitamin D3 analog. Tacalcitol is marketed under several names, including Curatoderm and Bonalfa.

thumb|Cholecalciferol, an example of a 9,10-secosteroid. [[IUPAC-approved carbon numbering and ring labeling is shown in the picture. Since secosteroids are derived from steroids, they retain the same labeling system as steroids. ]] thumb|right|250px|The parent steroid skeleton. The B-ring of the parent steroid is broken between C9 and C10 to yield D vitamins.

Dihydrotachysterol (DHT) is a synthetic vitamin D analog activated in the liver that does not require renal hydroxylation like vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). DHT has a rapid onset of action (2 hours), a shorter half-life, and a greater effect on mineralization of bone salts than does vitamin D.

Paricalcitol (chemically it is 19-nor-1,25-(OH)2-vitamin D2. Marketed by Abbott Laboratories under the trade name Zemplar) is a drug used for the prevention and treatment of secondary hyperparathyroidism (excessive secretion of parathyroid hormone) associated with chronic kidney failure. It is an analog of 1,25-dihydroxyergocalciferol, the active form of vitamin D2 (ergocalciferol).

chemical compound

chemical compound

24,25-Dihydroxycholecalciferol, also known as 24,25-dihydroxyvitamin D3, refers to a mixture of epimers hydroxycalcidiol and hydroxycalcidiol (abbreviated as and ) closely related to 1,25-dihydroxyvitamin D3, the active form of vitamin D3. Like vitamin D3 itself and calcifediol (25-hydroxyvitamin D3), it is inactive as a hormone both in vitro and in vivo. It was first identified in 1972 in the laboratory of Hector DeLuca and Michael F. Holick.

Doxercalciferol (or 1-hydroxyergocalciferol, trade name Hectorol) is drug for secondary hyperparathyroidism and metabolic bone disease. It is a synthetic analog of ergocalciferol (vitamin D2). It suppresses parathyroid synthesis and secretion.

Eldecalcitol is an analog of calcitriol, the active form of vitamin D.

3,4-DHSA is an organic compound which is the intermediate product of the metabolism of cholesterol, by the bacteria most commonly responsible for tuberculosis (Mycobacterium tuberculosis). 3,4-DHSA is an acronym for 3,4-dihydroxy-9,10-seco-androst-1,3,5(10)-triene-9,17-dione, the official name of this substance. It is classified as a secosteroid, since one of the four rings of cholesterol from which it is derived is broken.