Wikipedia:WikiProject Chemicals/Chembox validation/VerifiedDataSandbox and Retinyl palmitate: Difference between pages

{{Short description|Vitamin A chemical compound}}

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| ImageFile=Retinyl palmitate.png

| ImageFileL2=Retinyl palmitate spacefill.png

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| IUPACName=Retinyl hexadecanoate

| SystematicName=(2''E'',4''E'',6''E'',8''E'')-3,7-Dimethyl-9-(2,6,6-trimethylcyclohex-1-en-1-yl)nona-2,4,6,8-tetraen-1-yl hexadecanoate

| OtherNames=Retinol palmitate

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| ChEBI = 17616

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| ChEMBL = 1675

| PubChem=5280531

| KEGG=D00164

| SMILES = CC1(C)CCCC(\C)=C1\C=C\C(\C)=C\C=C\C(\C)=C\C(=O)OC(=O)CCCCCCCCCCCCCCC

| Formula=C₃₆H₆₀O₂

| MolarMass=524.86 g/mol

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| Solubility=In [[water]], [[ethanol]] and [[ethers]]<ref>{{cite book|publisher=CRC Press|author1=William M. Haynes|date=2014–2015|isbn=978-1-4822-08672|edition=95th|page=622|title=[[CRC Handbook of Chemistry and Physics]]}}.</ref>

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'''Retinyl palmitate''', or '''vitamin A palmitate,''' is the [[ester]] of [[retinol]] ([[vitamin A]]) and [[palmitic acid]], with formula C₃₆H₆₀O₂. It is the most abundant form of vitamin A storage in animals.<ref name=pmid23625372>{{cite journal |last1=O'Byrne |first1=SM |last2=Blaner |first2=WS |title=Retinol and retinyl esters: biochemistry and physiology. |journal=Journal of Lipid Research |date=July 2013 |volume=54 |issue=7 |pages=1731–43 |doi=10.1194/jlr.R037648 |doi-access=free |pmid=23625372 |pmc=3679378}}</ref>

An alternate spelling, '''retinol palmitate''', which violates the '''-yl''' organic chemical naming convention for [[ester]]s, is also frequently seen.

In 2021, vitamin A was the 298th most commonly prescribed medication in the United States, with more than 500,000 prescriptions.<ref>{{cite web | title=The Top 300 of 2021 | url=https://clincalc.com/DrugStats/Top300Drugs.aspx | website=ClinCalc | access-date=14 January 2024 | archive-date=15 January 2024 | archive-url=https://web.archive.org/web/20240115223848/https://clincalc.com/DrugStats/Top300Drugs.aspx | url-status=live }}</ref><ref>{{cite web | title = Vitamin A - Drug Usage Statistics | website = ClinCalc | url = https://clincalc.com/DrugStats/Drugs/VitaminA | access-date = 14 January 2024}}</ref>

== Biology ==

Animals use long-chain esters of vitamin A, most abundantly the palmitate form, as a form of vitamin A storage. The storage reaction is catalyzed by [[Lecithin retinol acyltransferase|LRAT]], and the inverse is catalyzed by [[Retinyl-palmitate esterase|REH]].<ref name=pmid23625372/> The esters are also intermediates in the [[visual cycle]]: [[RPE65]] isomerizes the retinyl part to 11-cis-retinal.<ref name=pmid23625372/>

==Uses==

Vitamin A palmitate is a common [[vitamin supplement]], available in both oral and [[Injection (medicine)|injectable]] forms for treatment of [[vitamin A deficiency]], under the brand names Aquasol A, Palmitate A and many others. It is a constituent of intra ocular treatment for dry eyes at a concentration of 138&nbsp;μg/g (VitA-Pos) by Ursapharm. It is a pre-formed version of vitamin A; therefore, the intake should not exceed the Recommended Dietary Allowance (RDA). Overdosing preformed Vitamin A forms such as retinyl palmitate leads to adverse physiological reactions ([[hypervitaminosis A]]).<ref>[http://lpi.oregonstate.edu/infocenter/vitamins/vitaminA Vitamin A], Linus Pauling Institute</ref>

Retinyl palmitate is used as a source of [[vitamin A]] added to low fat [[milk]] and other dairy products to replace the vitamin content lost through the removal of milk fat. Palmitate is attached to the alcohol form of vitamin A, [[retinol]], in order to make vitamin A stable in milk.{{Citation needed|date=July 2007}}

Retinyl palmitate is also a constituent of some topically applied skin care products. After its absorption into the skin, retinyl palmitate is converted to retinol, and ultimately to [[retinoic acid]] (the active form of vitamin A present in Retin-A), though neither its skin absorption<ref>{{Cite journal

| author = E. A. Duell, S. Kang & J. J. Voorhees

| title = Unoccluded retinol penetrates human skin in vivo more effectively than unoccluded retinyl palmitate or retinoic acid

| journal = [[The Journal of Investigative Dermatology]]

| volume = 109

| issue = 3

| pages = 301–305

| year = 1997

| pmid = 9284094

| doi = 10.1111/1523-1747.ep12335788

| doi-access = free

}}</ref> nor its conversion<ref name="BoehnleinSakr1994">{{cite journal|last1=Boehnlein|first1=James|last2=Sakr|first2=Adel|last3=Lichtin|first3=J. Leon|last4=Bronaugh|first4=Robert L.|journal=Pharmaceutical Research|title=Characterization of Esterase and Alcohol Dehydrogenase Activity in Skin. Metabolism of Retinyl Palmitate to Retinol (Vitamin A) During Percutaneous Absorption|volume=11|issue=8|year=1994|pages=1155–1159|issn=0724-8741|doi=10.1023/A:1018941016563|pmid=7971717|s2cid=25458156}}</ref> is very effective.

==Carcinogenicity controversy==

New York Senator [[Chuck Schumer]] has called attention to the fact that high doses of topical retinyl palmitate were shown to accelerate cancer in lab animals,<ref>{{cite news | url = http://www.nydailynews.com/lifestyle/health/2010/06/14/2010-06-14_chuck_cool_on_sunscreen.html | title = Possible link between ingredient in sunscreen and skin cancer: Schumer | newspaper = [[New York Daily News]] | date = June 14, 2010}}</ref> fueling the sunscreen controversy in the popular press.<ref name="auto">{{cite journal | pmid = 20692724 | year = 2010 | last1 = Wang | first1 = SQ | last2 = Dusza | first2 = SW | last3 = Lim | first3 = HW | title = Safety of retinyl palmitate in sunscreens: a critical analysis. | volume = 63 | issue = 5 | pages = 903–6 | doi = 10.1016/j.jaad.2010.07.015 | journal = Journal of the American Academy of Dermatology}}</ref> One toxicological analysis determined that "there is no convincing evidence to support the notion that [retinyl palmitate] in sunscreens is carcinogenic."<ref name="auto"/> A technical report issued thereafter by the [[National Toxicology Program]] concluded that diisopropyl adipate increased incidence of skin tumors in mice, and the addition of either [[retinoic acid]] or retinyl palmitate both exacerbated the rate and frequency of tumors.<ref>[[National Toxicology Program]]. (2012). NTP technical report on the photocarcinogenesis study of retinoic acid and retinyl palmitate [CAS Nos. 302-79-4 (All-trans-retinoic acid)

and 79-81-2 (All-trans-retinyl palmitate)] in SKH-1 mice (Simulated solar light and topical application study). Available at http://ntp.niehs.nih.gov/ntp/htdocs/LT_rpts/TR568_508.pdf. Accessed September 19, 2013.</ref>

==Teratogenicity==

World Health Organization recommendation on Maternal Supplementation During Pregnancy states that "health benefits are expected for the mother and her developing fetus with little risk of detriment to either, from a daily supplement not exceeding 10,000&nbsp;IU [preformed] vitamin A (3000&nbsp;μg [[retinol equivalent|RE]]) at any time during pregnancy."<ref>{{citation |url=http://whqlibdoc.who.int/hq/1998/WHO_NUT_98.4_eng.pdf |title=Safe vitamin A dosage during pregnancy and lactation |publisher=[[World Health Organization]] (WHO) |year=1998}}.</ref> Preformed Vitamin A refers to retinyl palmitate and retinyl acetate.

==See also==

* [[Vitamin A]]

* [[Retinyl acetate]]

* [[Vitamin supplement]]

==References==

{{Reflist}}

{{Retinoid receptor modulators}}

[[Category:Antioxidants]]

[[Category:Cyclohexenes]]

[[Category:Palmitate esters]]

[[Category:Retinoids]]

[[Category:Vitamins]]

[[Category:Orphan drugs]]