Tretinoin

"ATRA" redirects here. For the act that resolved the 2012 U.S. fiscal cliff, see American Taxpayer Relief Act of 2012.

Tretinoin

Systematic (IUPAC) name
retinoic acid
Clinical data
Trade names	Avita, Renova, Retin-a
AHFS/Drugs.com	monograph
MedlinePlus	a682437
Licence data	US Daily Med:link
Pregnancy cat.	C(topical), D(oral)(US), X(oral)(Aus)
Legal status	Prescription Only (S4) (AU) POM (UK) ℞-only (US)
Routes	Topical, oral
Pharmacokinetic data
Protein binding	> 95%
Half-life	0.5-2 hours
Identifiers
CAS number	302-79-4 Y
ATC code	D10AD01 L01XX14
PubChem	CID 444795
IUPHAR ligand	2644
DrugBank	DB00755
ChemSpider	392618 Y
UNII	5688UTC01R Y
KEGG	D00094 Y
ChEBI	CHEBI:15367 Y
ChEMBL	CHEMBL38 Y
Chemical data
Formula	C20H28O2
Mol. mass	300.4412 g/mol
SMILES O=C(O)\C=C(\C=C\C=C(\C=C\C1=C(\CCCC1(C)C)C)C)C
InChI InChI=1S/C20H28O2/c1-15(8-6-9-16(2)14-19(21)22)11-12-18-17(3)10-7-13-20(18,4)5/h6,8-9,11-12,14H,7,10,13H2,1-5H3,(H,21,22)/b9-6+,12-11+,15-8+,16-14+ Y Key:SHGAZHPCJJPHSC-YCNIQYBTSA-N Y
Physical data
Melt. point	180 °C (356 °F)
Y (what is this?)  (verify)

Tretinoin is the carboxylic acid form of vitamin A and is also known as all-trans retinoic acid or ATRA. It is a first generation topical retinoid commonly used to treat acne vulgaris and keratosis pilaris. It is available as a cream or gel (brand names Aberela, Airol, Renova, Atralin, Retin-A, Avita, Retacnyl, Refissa, ReTrieve, or Stieva-A). It is also used to treat acute promyelocytic leukemia (APL), and is sold for this indication by Roche under the brand name Vesanoid. It is also available as a generic.

Mechanism of action

Although tretinoin activates three members of the retinoid acid (RAR) nuclear receptors (RARα, RARβ, and RARγ) which may act to modify gene expression, subsequent protein synthesis, and epithelial cell growth and differentiation, it has not been established whether the clinical effects of tretinoin are mediated through activation of retinoic acid receptors, other mechanisms, or both.

Uses

Dermatology

Tretinoin is most commonly used as a form of acne treatment. It was the first retinoid developed for this type of topical use.^{[citation needed]} Tretinoin is the best studied retinoid in the treatment of photoaging. It is used by some as a hair loss treatment and is a component of many commercial products that are advertised as being able to slow skin aging or remove wrinkles.^{[citation needed]} Topical tretinoin is also used to treat and reduce the appearance of stretch marks by increasing collagen production in the dermis.

Leukemia

Tretinoin, marketed as Vesanoid, is used to treat at least one form of cancer (acute promyelocytic leukemia, also called acute myeloid leukemia subtype M3), usually together with other drugs, by causing the immature promyelocytes to differentiate (i.e. mature). The pathology of the leukemia is due to the highly proliferative immature cells; retinoic acid drives these cells to develop into functional cells, which helps to alleviate the disease.^{[citation needed]} It is usually prescribed for 15 days every three months at about 8–10 10-mg capsules per day.^{[citation needed]}

Clinical pharmacology

Successfully treating acute promyelocytic leukemia (APL) with Tretinoin was a major breakthrough in APL therapy. It works in APL because the majority of cases involve a chromosomal translocation of chromosomes 15 and 17, which causes genetic fusion of the retinoic acid receptor (RAR) gene to the promyelocytic leukemia (PML) gene. This fusion PML-RAR protein is responsible for preventing immature myeloid cells from differentiating into more mature cells. This block in differentiation is thought to cause leukemia. ATRA acts on PML-RAR to lift this block, causing the immature promyelocytes to differentiate to normal mature blood cells thus decreasing promyelocytes.^{[citation needed]}

Side effects

In dermatological use

When used, dryness or increased sensitivity to sunlight of the affected skin may occur. More sensitive patients may also experience redness, scaling, itching, and burning. A gradual increase in the frequency and amount of tretinoin application is best, as this allows one's skin to adequately adjust to the drug. Patients should be careful to follow their physician's recommendations when beginning a round of treatment.

This product increases the risk of sunburn; care should be taken (shade, sunscreen, etc.) to protect treated skin from overexposure to ultraviolet light.

Because usage of tretinoin may cause thinning of the skin, it is strongly recommended that patients who are using the drug abstain from hair removal waxing.^{[citation needed]} The wax will, when removed, pull off the top level of epithelium (skin) with it, leaving a red, inflamed, sore mark for several days.^{[citation needed]} Tweezing or threading (epilation) is a viable option for hair removal. The recommended timeframe to wait for a waxing treatment after using tretinoin varies from source to source; anywhere from five days to three months have been reported. Patients should consult with their esthetician and dermatologist to discuss the best hair removal options during or after tretinoin use.^{[citation needed]}

In leukemia use

There is a unique complication of retinoic acid syndrome in patients with acute promyelocytic leukemia. This is associated with the development of dyspnea, fever, weight gain, peripheral edema and is treated with dexamethasone. The etiology of retinoic acid syndrome has been attributed to capillary leak syndrome from cytokine release from the differentiating promyelocytes.

Teratogenicity

It is a teratogen, and therefore can cause birth defects and tests have shown increases in fetal skull abnormalities in rats. Women who are or may be pregnant, or who are seeking to become pregnant, are therefore warned against using it. This teratogenic effect is caused by the interference of the exogenous retinoic acid with endogenous retinoic acid signaling, which plays a role in patterning the developing embryo. However the risks of topical tretinoin to the fetus seems to be limited.

Research uses

A study published by the European Respiratory Journal in 2002, suggested tretinoin can reverse the effects of emphysema in mice by returning elasticity (and regenerating lung tissue through gene mediation) to the alveoli. Studies suggested this might form a promising treatment in human emphysema patients. However, a newer follow-up study done in 2006 found inconclusive results ("no definitive clinical benefits") using vitamin A (retinoic acid) in treatment of emphysema in humans and stated further research is needed to reach conclusions on this treatment.

See also

• Baldness treatments
• Hypervitaminosis A syndrome
• Talarozole, an experimental drug potentiating the effects of tretinoin

Manufacture

Lewin, Anita H.; Whaley, M. Glenn; Parker, Steven R.; Carroll, F. Ivy; Moreland, Charles G. (May 1982). "12-Carboxyretinoic acids. Synthesis and structure". The Journal of Organic Chemistry 47 (10): 1799–1807. doi:10.1021/jo00349a001. 

External links

• "Prescription Medications for Treating Acne". American Academy of Dermatology. 
• Prescribing Information for Retin-A Micro Ortho
• Tretinoin AHFS Consumer Medication Information at PubMed Health
• Tretinoin Cream Prescribing Information Drugs.com
• Retin-A Cream, Gel, Liquid Prescribing Information Drugs.com