Calcitriol
2200872
212112096
2008-05-13T14:15:17Z
141.219.48.137
corrected error: Calcitiol is not Vit D3.
{{drugbox |
| image = calcitriol.png
| width = 280
| IUPAC_name = (1''R'',3''S'')- 5-<nowiki>[2-[(</nowiki>1R,3a''R'',7a''S'')-1- <nowiki>[</nowiki>(2''R'')-6-hydroxy-6-methyl-heptan-2-yl<nowiki>]</nowiki>- <br />7a-methyl-2,3,3a,5,6,7-hexahydro-1''H''- inden-4-ylidene]ethylidene]-<br /> 4-methylidene-cyclohexane-1,3-diol
| CAS_number = 32222-06-3
| ATC_prefix= A11
| ATC_suffix= CC04
| ATC_supplemental = {{ATC|D05|AX03}}
| PubChem = 134070
| DrugBank = APRD00246
| C=27 | H=44 | O=3
| molecular_weight = 416.64 g/mol
| bioavailability =
| metabolism = [[Renal]]
| elimination_half-life = 5–8 hours
| excretion = Renal
| pregnancy_category = B3 <small>([[Australia|Au]])</small>, C <small>([[United States|U.S.]])</small>
| legal_status = S4 <small>(Au)</small>, POM <small>([[United Kingdom|UK]])</small>
| routes_of_administration = Oral, [[intravenous|IV]], topical
}}
'''Calcitriol''' ([[International Nonproprietary Name|INN]]) ({{pronEng|ˌkælsɨˈtraɪɒl/, /ˌkælˈsɨtriːɒl}}) or '''1,25-dihydroxycholecalciferol''' (abbreviated '''1,25-(OH)<sub>2</sub>D<sub>3</sub>''') (also known as calitrol) is the active form of [[vitamin D]] found in the body (1,25(OH)2D3). It increases the absorption of [[calcium]] and [[phosphate]] from the [[gastrointestinal tract]] and [[kidneys]] and inhibits release of [[calcitonin]].
Calcitriol is marketed under various trade names including '''Rocaltrol''' ([[Hoffman-La Roche|Roche]]), '''Calcijex''' ([[Abbott Laboratories|Abbott]]) and '''Decostriol''' (Mibe, Jesalis).
==Production and function==
It is produced in the kidneys via [[25-Hydroxyvitamin D3 1-alpha-Hydroxylase]] by conversion from 25-hydroxycholecalciferol ([[calcidiol]]).
This is stimulated by a decrease in serum [[calcium]] and/or [[phosphate]] (PO<sub>4</sub><sup>3−</sup>), and an increase in [[parathyroid hormone]] (PTH) and/or [[prolactin]] levels. It increases blood calcium levels by increasing the absorption of calcium and phosphate from the [[gastrointestinal tract]], increasing calcium and phosphate reabsorption in the kidneys, and inhibiting the release of [[calcitonin]]. Calcitriol acts in concert with [[parathyroid hormone]] (PTH).
Calcitriol is also commonly used as a medication in the treatment of [[hypocalcemia]] and [[osteoporosis]].
==Metabolism==
Calcitriol becomes [[calcitroic acid]] through the action of 24-hydroxylase. Calcitroic acid is excreted in the urine.
==Indications==
Calcitriol is indicated for:<ref name="AMH2006">Rossi S, editor. [[Australian Medicines Handbook]] 2006. Adelaide: Australian Medicines Handbook; 2006. ISBN 0-9757919-2-3</ref>
*Treatment of [[hypocalcaemia]] – [[hypoparathyroidism]], [[osteomalacia]] (adults), [[rickets]] (infants, children), [[renal osteodystrophy]], chronic [[renal dialysis]]
*Treatment of [[osteoporosis]]
*Prevention of [[corticosteroid]]-induced osteoporosis
Calcitriol is also sometimes used topically in the treatment of [[psoriasis]], however the evidence to support its efficacy is inconclusive.<ref name="MicromedexDrugdex">Calcitriol. In: Klasco RK, editor. Drugdex system. vol 128. Greenwood Village (CO): Thomson Micromedex; 2006.</ref> The vitamin D analogue [[calcipotriol]] is more commonly used for psoriasis.
==Adverse effects==
The main [[adverse drug reaction]] associated with calcitriol therapy is [[hypercalcaemia]] – early symptoms include: nausea, vomiting, constipation, [[anorexia (symptom)|anorexia]], [[apathy]], headache, thirst, sweating, and/or [[polyuria]]). Compared to other vitamin D compounds in clinical use ([[cholecalciferol]], [[ergocalciferol]]), calcitriol has a higher risk of inducing hypercalcaemia. However, such episodes may be shorter and easier to treat due to its relatively short [[elimination half-life|half-life]].<ref name="AMH2006" />
==See also==
* [[Vitamin D#Synthesis mechanism .28form 3.29]]
==Additional images==
<gallery>
Image:Calcitriol-Synthesis.png|Calcitriol synthesis
</gallery>
==References==
{{reflist}}
{{Hormones}}
{{Vitamin}}
{{Antipsoriatics}}
[[Category:Vitamins]]
[[Category:Secosteroids]]
[[de:Calcitriol]]
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[[es:Calcitriol]]
[[mk:Калцитриол]]
[[pl:Kalcytriol]]
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