Calcitriol is the active form of

vitamin D Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group are vitamin D3 (c ...

, normally made in the

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...

. It is also known as 1,25-dihydroxycholecalciferol. It is a

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

which binds to and activates the

vitamin D receptor The vitamin D receptor (VDR also known as the calcitriol receptor) is a member of the nuclear receptor family of transcription factors. Calcitriol (the active form of vitamin D, 1,25-(OH)2vitamin D3) binds to VDR, which then forms a heterodim ...

in the nucleus of the cell, which then increases the expression of many genes. Calcitriol increases blood

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...

(Ca²⁺) mainly by increasing the uptake of calcium from the

intestines The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...

. It can be given as a medication for the treatment of low blood calcium and

hyperparathyroidism Hyperparathyroidism is an increase in parathyroid hormone (PTH) levels in the blood. This occurs from a disorder either within the parathyroid glands (primary hyperparathyroidism) or as response to external stimuli (secondary hyperparathyroidism). ...

due to

kidney disease Kidney disease, or renal disease, technically referred to as nephropathy, is damage to or disease of a kidney. Nephritis is an inflammatory kidney disease and has several types according to the location of the inflammation. Inflammation can ...

, low blood calcium due to

hypoparathyroidism Hypoparathyroidism is decreased function of the parathyroid glands with underproduction of parathyroid hormone (PTH). This can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany (involuntary m ...

osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...

osteomalacia Osteomalacia is a disease characterized by the softening of the bones caused by impaired bone metabolism primarily due to inadequate levels of available phosphate, calcium, and vitamin D, or because of resorption of calcium. The impairment of bon ...

, and

familial hypophosphatemia X-linked hypophosphatemia (XLH) is an X-linked dominant form of rickets (or osteomalacia) that differs from most cases of dietary deficiency rickets in that vitamin D supplementation does not cure it. It can cause bone deformity including short st ...

, and can be taken by mouth or by

injection into a vein Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutri ...

. Excessive amounts or intake can result in weakness, headache, nausea, constipation,

urinary tract infections A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...

, and abdominal pain. Serious side effects may include

high blood calcium Hypercalcemia, also spelled hypercalcaemia, is a high calcium (Ca2+) level in the blood serum. The normal range is 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcemi ...

and

anaphylaxis Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the follow ...

. Regular blood tests are recommended after the medication is started and when the dose is changed. Calcitriol was identified as the active form of vitamin D in 1971 and the drug was approved for medical use in the United States in 1978. It is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

. In 2020, it was the 277th most commonly prescribed medication in the United States, with more than 1million prescriptions. It is on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health ...

Medical use

Calcitriol is prescribed for: * Treatment of

hypocalcaemia Hypocalcemia is a medical condition characterized by low calcium levels in the blood serum. The normal range of blood calcium is typically between 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L) while levels less than 2.1 mmol ...

–

(adults),

rickets Rickets is a condition that results in weak or soft bones in children, and is caused by either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications may ...

(infants, children),

renal osteodystrophy Renal osteodystrophy/adynamic bone disease is currently defined as an alteration of bone morphology in patients with chronic kidney disease (CKD). It is one measure of the skeletal component of the systemic disorder of chronic kidney disease-min ...

chronic kidney disease Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vo ...

* Treatment of

* Prevention of

corticosteroid-induced osteoporosis Steroid-induced osteoporosis is osteoporosis arising from the use of glucocorticoids (a class of steroid hormones) analogous to Cushing's syndrome but involving mainly the axial skeleton. The synthetic glucocorticoid prescription drug prednisone ...

Calcitriol has been used in an ointment for the treatment of

psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete ...

, although the

vitamin D analogue The active natural hormonal form of vitamin D is 1,25-dihydroxyvitamin D (1,25(OH)2D). This molecule and other naturally occurring forms of vitamin D, including its precursors and metabolites, have been modified to synthesize pharmaceuticals with p ...

calcipotriol Calcipotriol, also known as calcipotriene, is a synthetic derivative of calcitriol, a form of vitamin D. It is used in the treatment of psoriasis. It is safe for long-term application in psoriatic skin conditions. It was patented in 1985 and a ...

(calcipotriene) is more commonly used. Calcitriol has also been given by mouth for the treatment of psoriasis and

psoriatic arthritis Psoriatic arthritis is a long-term inflammatory arthritis that occurs in people affected by the autoimmune disease psoriasis. The classic feature of psoriatic arthritis is swelling of entire fingers and toes with a sausage-like appearance. Thi ...

. Research on the noncalcemic actions of calcitriol and other VDR-ligand analogs and their possible therapeutic applications has been reviewed.

Adverse effects

The main

adverse drug reaction An adverse drug reaction (ADR) is a harmful, unintended result caused by taking medication. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs. The meaning of this term ...

associated with calcitriol therapy is hypercalcemia – early symptoms include:

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the Human nose, nose. Vomiting can be the result of ailments like Food-poisoning, foo ...

constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...

anorexia Anorexia nervosa, often referred to simply as anorexia, is an eating disorder characterized by low weight, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin. ''Anorexia'' is a term of Gre ...

apathy Apathy is a lack of feeling, emotion, interest, or concern about something. It is a state of indifference, or the suppression of emotions such as concern, excitement, motivation, or passion. An apathetic individual has an absence of intere ...

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

thirst Thirst is the craving for potable fluids, resulting in the basic instinct of animals to drink. It is an essential mechanism involved in fluid balance. It arises from a lack of fluids or an increase in the concentration of certain osmolites, suc ...

pruritus Itch (also known as pruritus) is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of sensory experience. Itch has many similarities to pain, and while both are unpleasant ...

sweating Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distr ...

, and/or

polyuria Polyuria () is excessive or an abnormally large production or passage of urine (greater than 2.5 L or 3 L over 24 hours in adults). Increased production and passage of urine may also be termed diuresis. Polyuria often appears in conjunction wit ...

. Compared to other vitamin D compounds in clinical use (

cholecalciferol Cholecalciferol, also known as vitamin D3 and colecalciferol, is a type of vitamin D that is made by the skin when exposed to sunlight; it is found in some foods and can be taken as a dietary supplement. Cholecalciferol is made in the skin f ...

ergocalciferol Ergocalciferol, also known as vitamin D2 and nonspecifically calciferol, is a type of vitamin D found in food and used as a dietary supplement. As a supplement it is used to prevent and treat vitamin D deficiency. This includes vitamin D defici ...

), calcitriol has a higher risk of inducing hypercalcemia. However, such episodes may be shorter and easier to treat due to its relatively short

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...

. High calcitriol levels may also be seen in human disease states in patients not on supplementation. In someone with

hypercalcaemia Hypercalcemia, also spelled hypercalcaemia, is a high calcium (Ca2+) level in the blood serum. The normal range is 2.1–2.6 mmol/L (8.8–10.7 mg/dL, 4.3–5.2 mEq/L), with levels greater than 2.6 mmol/L defined as hypercalcemia ...

and high calcitriol levels, low intact

parathyroid hormone Parathyroid hormone (PTH), also called parathormone or parathyrin, is a peptide hormone secreted by the parathyroid glands that regulates the serum calcium concentration through its effects on bone, kidney, and intestine. PTH influences bone ...

levels are usually present. The major conditions with hypercalcaemia due to elevated calcitriol levels are

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enlar ...

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in ...

and

sarcoidosis Sarcoidosis (also known as ''Besnier-Boeck-Schaumann disease'') is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly af ...

where excess production occurs due to ectopic 25(OH)D-1-hydroxylase (CYP27B1) expressed in

macrophages Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer ce ...

. Other conditions producing similar findings including: * Fungal infections; Pneumocystis jiroveci, histoplasmosis, coccidioidomycosis, paracoccidioidomycosis, candidiasis * Other granulomatous conditions; PR3+ vasculitis,

Crohn's disease Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea (which may be bloody if inflammation is severe), fever, abdominal distension ...

, acute granulomatous pneumonia, talc granuloma, silicone-induced granuloma, BCG-associated, granulomatous hepatitis, paraffin-associated granuloma * Genetic conditions; Williams syndrome, pseudoxanthoma elasticum, CYP24A1 mutation (adult / infantile), SLC34A1 mutation * Miscellaneous; mycobacterium avium, leprosy, lipoid pneumonia, cat scratch fever, berylliosis Some plants contain glycosides of 1,25-dihydroxycholecalciferol. Consumption of these glycosides by grazing animals leads to vitamin D toxicity, resulting in

calcinosis Calcinosis is the formation of calcium deposits in any soft tissue. It is a rare condition that has many different causes. These range from infection and injury to systemic diseases like kidney failure. Types Dystrophic calcification The most c ...

, the deposition of excessive calcium in soft tissues. Three rangeland plants, ''

Cestrum diurnum ''Cestrum diurnum'' is a species of ''Cestrum'', native to the West Indies. Common names include ''day-blooming cestrum'', ''day-blooming jessamine'', and ''day-blooming jasmine''. Also known as Din ka Raja (king of the day), in Hindi. The scent ...

'', ''

Solanum malacoxylon ''Solanum glaucophyllum'' is a species of plant in the family Solanaceae The Solanaceae , or nightshades, are a family of flowering plants that ranges from annual and perennial herbs to vines, lianas, epiphytes, shrubs, and trees, and includ ...

'', and ''

Trisetum flavescens ''Trisetum flavescens'', the yellow oatgrass or golden oat grass, is a species of grass in the family Poaceae. It is native to Europe, Asia, and North Africa. It can be found elsewhere, such as sections of North America, where it was introduce ...

'' are known to contain these glycosides. Of these, only ''C. diurnum'' is found in the U.S., mainly in Florida.

Mechanism of action

Calcitriol increases blood calcium levels ([]) by: * Promoting absorption of dietary calcium from the gastrointestinal tract. * Increasing Renal tubule, renal tubular reabsorption of calcium, thus reducing the loss of calcium in the urine. * Stimulating release of calcium from bone. For this it acts on the specific type of bone cells referred to as

osteoblasts Osteoblasts (from the Greek language, Greek combining forms for "bone", ὀστέο-, ''osteo-'' and βλαστάνω, ''blastanō'' "germinate") are cell (biology), cells with a single Cell nucleus, nucleus that synthesize bone. However, in the p ...

, causing them to release

RANKL Receptor activator of nuclear factor kappa- ligand (RANKL), also known as tumor necrosis factor ligand superfamily member 11 (TNFSF11), TNF-related activation-induced cytokine (TRANCE), osteoprotegerin ligand (OPGL), and osteoclast differentiati ...

, which in turn activates

osteoclasts An osteoclast () is a type of bone cell that breaks down bone tissue. This function is critical in the maintenance, repair, and remodeling of bones of the vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated prote ...

. Calcitriol acts in concert with

(PTH) in all three of these roles. For instance, PTH also indirectly stimulates osteoclasts. However, the main effect of PTH is to increase the rate at which the kidneys excrete

inorganic phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...

(P_i), the

counterion 160px, Polystyrene sulfonate, a cation-exchange resin, is typically supplied with as the counterion.">cation-exchange_resin.html" ;"title="Polystyrene sulfonate, a cation-exchange resin">Polystyrene sulfonate, a cation-exchange resin, is typical ...

of . The resulting decrease in serum phosphate causes hydroxyapatite (Ca₅(PO₄)₃OH) to dissolve out of bone, thus increasing serum calcium. PTH also stimulates the production of calcitriol (see below). Many of the effects of calcitriol are mediated by its interaction with the

calcitriol receptor The vitamin D receptor (VDR also known as the calcitriol receptor) is a member of the nuclear receptor family of transcription factors. Calcitriol (the active form of vitamin D, 1,25-(OH)2vitamin D3) binds to VDR, which then forms a heterodim ...

, also called the vitamin D receptor or VDR. For instance, the unbound inactive form of the calcitriol receptor in intestinal epithelial cells resides in the

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...

. When calcitriol binds to the receptor, the

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

-receptor complex translocates to the

cell nucleus The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, h ...

, where it acts as a

transcription factor In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fu ...

promoting the expression of a gene encoding a

calcium binding protein Calcium-binding proteins are proteins that participate in calcium cell signalling pathways by binding to Ca2+, the calcium ion that plays an important role in many cellular processes. Calcium-binding proteins have specific domains that bind to cal ...

. The levels of the calcium binding protein increase enabling the cells to actively transport more calcium () from the intestine across the

intestinal mucosa The gastrointestinal wall of the gastrointestinal tract is made up of four layers of specialised tissue. From the inner cavity of the gut (the lumen) outwards, these are: # Mucosa # Submucosa # Muscular layer # Serosa or adventitia The mucosa is ...

into the blood. Alternative, ''non-genomic'' pathways may be mediated through either

PDIA3 Protein disulfide-isomerase A3 (PDIA3), also known as glucose-regulated protein, 58-kD (GRP58), is an isomerase enzyme. This protein localizes to the endoplasmic reticulum (ER) and interacts with lectin chaperones calreticulin and calnexin (CNX) ...

or VDR. The maintenance of electroneutrality requires that the transport of ions catalyzed by the intestinal epithelial cells be accompanied by counterions, primarily inorganic phosphate. Thus calcitriol also stimulates the intestinal absorption of phosphate. The observation that calcitriol stimulates the release of calcium from bone seems contradictory, given that sufficient levels of serum calcitriol generally prevent overall loss of calcium from bone. It is believed that the increased levels of serum calcium resulting from calcitriol-stimulated intestinal uptake causes bone to take up more calcium than it loses by hormonal stimulation of osteoclasts. Only when there are conditions, such as dietary calcium deficiency or defects in intestinal transport, which result in a reduction of serum calcium does an overall loss of calcium from bone occur. Calcitriol also inhibits the release of

calcitonin Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates. in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing the ...

, a hormone which reduces blood calcium primarily by inhibiting calcium release from bone.

Biosynthesis and its regulation

Calcitriol is produced in the cells of the

proximal tubule The proximal tubule is the segment of the nephron in kidneys which begins from the renal pole of the Bowman's capsule to the beginning of loop of Henle. It can be further classified into the proximal convoluted tubule (PCT) and the proximal straig ...

of the

nephron The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure ...

in the kidneys by the action of 25-hydroxyvitamin D₃ 1-alpha-hydroxylase, a

mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...

oxygenase An oxygenase is any enzyme that oxidizes a substrate by transferring the oxygen from molecular oxygen O2 (as in air) to it. The oxygenases form a class of oxidoreductases; their EC number is EC 1.13 or EC 1.14. Discoverers Oxygenases were disco ...

and an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

which catalyzes the

hydroxylation In chemistry, hydroxylation can refer to: *(i) most commonly, hydroxylation describes a chemical process that introduces a hydroxyl group () into an organic compound. *(ii) the ''degree of hydroxylation'' refers to the number of OH groups in a ...

of 25-hydroxycholecalciferol (calcifediol) in the 1-alpha position. The activity of this enzyme is stimulated by PTH. This is an important control point in Ca²⁺ homeostasis. Additional effects on the production of calcitriol include an increase by

prolactin Prolactin (PRL), also known as lactotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. Prolactin is secreted from the pit ...

, a hormone which stimulates

lactogenesis A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in primat ...

(the formation of milk in

mammary glands A mammary gland is an exocrine gland in humans and other mammals that produces milk to feed young offspring. Mammals get their name from the Latin word ''mamma'', "breast". The mammary glands are arranged in organs such as the breasts in prima ...

), a process which requires large amounts of calcium. Activity is also decreased by high levels of serum phosphate and by an increase in the production of the hormone

FGF23 Fibroblast growth factor 23 (FGF23) is a protein and member of the fibroblast growth factor (FGF) family which participates in the regulation of phosphate in plasma and vitamin D metabolism. In humans it is encoded by the gene. FGF23 decreases rea ...

by osteocyte cells in bone. Calcitriol is also produced outside the kidney in small amounts by many other tissues including

placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mater ...

and activated

. When the drug

alfacalcidol Alfacalcidol (or 1-hydroxycholecalciferol) is an analogue of vitamin D used for supplementation in humans and as a poultry feed additive. Alfacalcidol has a weaker impact on calcium metabolism and parathyroid hormone levels than calcitriol, howev ...

is used, 25-hydroxylation in the liver produces calcitriol as the active metabolite. This will produce greater effects than other vitamin D precursors in patients with kidney disease who have loss of the renal 1-alpha-hydroxylase.

Interactive pathway map

Metabolism

The halflife of calcitriol in the body is measured in hours, unlike its precursor calcifediol, whose halflife is measured in weeks. Calcitriol is inactivated by further hydroxylation to form 1,24,25-trihydroxyvitamin D,

calcitroic acid Calcitroic acid (1α-hydroxy-23-carboxy-24,25,26,27-tetranorvitamin D3) is a major metabolite of 1α,25-dihydroxyvitamin D3 (calcitriol). Often synthesized in the liver and kidneys, calcitroic acid is generated in the body after vitamin D is fir ...

. This occurs through the action of the CYP24A1 24-hydroxylase. Calcitroic acid is more soluble in water and is excreted in bile and urine.

History

It was first identified in 1971 by Michael F. Holick working in the laboratory of

Hector DeLuca Hector F. DeLuca, born in Pueblo, Colorado in 1930, is an emeritus University of Wisconsin–Madison professor and former chairman of the university's biochemistry department. DeLuca is well known for his research in involving Vitamin D, from wh ...

, and also by

Tony Norman Anthony Joseph Norman (born 24 February 1958) is a Welsh former professional footballer who played as a goalkeeper for Hull City, Sunderland and Huddersfield Town. He holds the record for consecutive appearances for Hull City, playing 226 cons ...

and colleagues.

Names

Calcitriol refers specifically to 1,25-dihydroxycholecalciferol. Because

already has one hydroxyl group, only two (1,25) are further specified in this nomenclature, but in fact there are three (1,3,25-triol), as indicated by the name ''calcitriol''. The 1-hydroxy group is in the alpha position, and this may be specified in the name, for instance in the abbreviation 1α,25-(OH)₂D₃. Calcitriol is, strictly, the 1-hydroxylation product of

calcifediol 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-hydroxylas ...

(25-OH vitamin D₃), derived from cholecalciferol (vitamin D₃), rather than the product of hydroxylations of

(vitamin D₂). 1α,25-Dihydroxyergocalciferol (ercalcitriol) should be used for the vitamin D₂ product. However, the terminology of 1,25-dihydroxyvitamin D, or 1,25(OH)₂D, is often used to refer to both types of active forms of vitamin D. Indeed, both bind to the vitamin D receptor and produce biological effects. In clinical use, the differences are unlikely to have major importance. Calcitriol is marketed as a pharmaceutical for medical use under various trade names including Rocaltrol (

Roche F. Hoffmann-La Roche AG, commonly known as Roche, is a Swiss multinational healthcare company that operates worldwide under two divisions: Pharmaceuticals and Diagnostics. Its holding company, Roche Holding AG, has shares listed on the SIX ...

), Calcijex ( Abbott), Decostriol (Mibe, Jesalis), Vectical (

Galderma Galderma S.A. is a Swiss pharmaceutical company specializing in dermatological treatments and skin care products. Formerly a subsidiary of L'Oréal and Nestlé, it has been held by a consortium of private institutional investors since 2019. Gal ...

), and Rolsical (

Sun Pharma Sun Pharmaceutical Industries Limited (d/b/a Sun Pharma) is an Indian multinational pharmaceutical company headquartered in Mumbai, that manufactures and sells pharmaceutical formulations and active pharmaceutical ingredients (APIs) in more th ...

References

External links

* {{Portal bar , Medicine Wikipedia medicine articles ready to translate Secosteroids Vitamin D Hoffmann-La Roche brands World Health Organization essential medicines