Retinoic Acid Tretinoin

Generally used at a concentration of 0.05-1% with minimal side effects (erythema and desquamation), retinoic acid has to be applied once a day, usually nightly. It does not suppress melanogenesis, but accelerates epidermal turn- 

Chemical peels can be performed both in fair and dark skin types, but in the latter case a ten- 

Different agents are reported to be effective, but in our experience, the best options are  

Patients should undergo a superficial peeling every 2 weeks or a medium peeling every month. With a medium chemical peel, the application of the solution must be reduced in time in order to avoid overpeel. 

It is important that, 3 weeks before starting peeling treatment and 10 days after each treatment, the patient does the following routine  

---

Retinoic acid (RA) describes a group of vitamin A acid (synonym Vitamin A1 acid) derivatives such as all-irans-retinoic acid (tretinoin), 9-cis-retinoic acid and 13-cis retinoic acid (isotretinoin). Retinoic acids act through binding to retinoic acid and retinoid X response elements. 

Kimbrough-Green CK, Griffiths CE, Finkel LJ, et al (1994) Topical retinoic acid (Tretinoin) for melasma in black patients-a vehicle controlled clinical trial. Arch Dermatol 130 727-733... 

Metabolism - Following oral administration of isotretinoin, at least 3 metabolites have been identified in human plasma 4-oxo-isotretinoin, retinoic acid (tretinoin), and 4-oxo-retinoic acid (4-oxo-tretinoin). Retinoic acid and 13-c/s-retinoic P.1213... 

The past twenty years have witnessed considerable progress in the synthesis and use of other retinoid-like molecules related to vitamin A. The aromatic retinoid etretin (8.54) and its ester etretinate (8.55) had some effectiveness in the treatment of psoriasis, a disorder of skin. 13-cA-Retinoic acid (isotretinoin) produces sebaceous gland atrophy and could prove useful in the treatment of severe acne vulgaris. Although these compounds have toxic side effects and are not in regular use, they have opened up new therapeutic possibilities. Retinoic acid (tretinoin, 8.56) has been employed in the treatment of acne. 

Retinoic acid (vitamin A acid), in which the alcohol group has been oxidized, shares some but not all of the actions of retinol. Retinoic acid is ineffective in restoring visual or reproductive function in certain species in which retinol is effective. Flowever, retinoic acid is very potent in promoting growth and controlling differentiation and maintenance of epithelial tissue in vitamin A-deficient animals. Indeed, all-trans-retinoic acid (tretinoin) appears to be the active form of vitamin A in all tissues except the retina, and is 10- to 100-fold more potent than retinol in various systems in vitro. Isomerization of this compound in the body yields 13-n.v-rctinoic acid (isotretinoin), which is nearly as potent as tretinoin in many of its actions on epithelial tissues but may be as much as fivefold less potent in producing the toxic symptoms of hypervitaminosis A. 

Retinoids in Dermatology 13-Qs-retinoic acid (isotretinoin, Accutane ) is used orally, and all-trans-retinoic acid (Tretinoin ) topically, for treatment of severely disfiguring cystic acne. Etretinate (the trimethoxyphenyl analog of retinoic acid) and tazarotene (a receptor-specific retinoid) are used topically for the treatment of psoriasis. They are effective in cases in which other therapy has failed, and at lower levels than are required for the control of tumor development in experimental animals, although they have heen associated with hirth defects (Section 2.5.1.1 fohnson and Chandrarama, 1999). 

Oxidation of retinol produces retinoic acid tretinoin). The reaction is irreversible. Retinoic acid enters the portal blood, is transported bound to albumin, and is not stored to any great extent. The concentration of retinoic acid in plasma is normally 3-4 ng/mL. A biologically active metabolite, 5,6-epoxyretinoic acid, has been isolated from the intestinal mucosa of vitamin A-deficient rats following administration of H-retinoic acid. Several tissues have specific cellular retinoic acid-binding proteins (CRABPs). 

The potential of retinoic acid and other retinoids in the treatment of epithelial disorders and cancer has been the driving force in much of the work with retinoids. Already all-trons retinoic acid (Tretinoin) and 13-m-retinoic acid (Isotretinoin/Accutane) are approved in Europe and the United States for clinical use in the treatment of different forms of acne while Acitretin (R26) and its ethyl ester (etretinate) are used in the treatment of psoriasis. The use of retinoids in the treatment of photodamaged skin is also being investigated [19]. 

Toxicology Vitamin A hypervitaminosis can lead to clinical symptoms such as headache, nausea, in chronic cases disturbances of sleep, loss of appetite, loss of hair, bone swellings in the limbs however, all symptoms disappear when the consumption of vitamin A is reduced. Acute poisonings have been observed in, e.g., polar explorers after consumption of the extremely vitamin A,-rich polar bear liver. The metabolite of R., vitamin A acid (retinoic acid, tretinoin, C20H28O3, Mr 316.44, mp. 180-182 °C) can cause malformations and thus pregnant women should not consume more than 3.3 mg of vitamin A] per day Synthesis R. was obtained in the past from fish oils, which have contents of up to 17%, while it is now mostly produced synthetically . ... 

The morphologic changes observed in cultures of embryonic chick skin exposed to all-/ranj-retinoic acid (tretinoin, Dl) were reversible and both dose- and time-dependent. Keratinization was inhibited and fewer desmosomes and tono-filaments were seen. Golgi elements, rough endoplasmic reticulum, and polyribosomes were unusually prominent. Mucin granules formed and gland-like structures developed with intercellular canaliculi characterized by tight junctions, brush borders, and dense secretory contents (Peck et al., 1977). 

Wyss, R. Bucheli, F. Determination of endogenous levels of 13-cis-retinoic acid (isotretinoin), aU-trans-retinoic acid (tretinoin) and their 4-oxo metabolites in human and animal plasma by high-performance liquid chromatography with automated column switching and liltraviolet detection, J.Chromatogr.B,... 

Retinoids have multiple properties in embriogenesis, growth control and differentiation of adult tissues, reproduction, and sight. In dermatology their use is well established for psoriasis, hereditary disorders of keratinization, acne, and skin aging. The most commonly used retinoids are aH-trans retinoic acid (tretinoin used topically), 13-cis retinoic acid [isotretinoin used both orally and topically), retinaldehyde/retinal and retinol [both of which are used topically). In addition there are the synthetic retinoids etretinate, acitretin, adapalene, tazarotene, etc. 

---