Product Code Database
The retinoids are a class of chemical compounds that are natural derivatives of vitamin A or are chemically related to it. Synthetic retinoids are utilized in cosmetic formulations, clinical dermatology, and the treatment of some forms of cancer.
Retinoids have many important functions throughout the body, including in vision, regulation of skin proliferation and differentiation, growth of bone tissue, immune function, and male fertility.
The biology of retinoids is complex, having well-documented effectiveness in the management of conditions ranging from acute promyelocytic leukemia to acne to photoaging. On the other hand, retinoids may be involved in metabolic dysfunction and, at least in some forms, carcinogenesis.
| retinol, retinal, tretinoin (retinoic acid), isotretinoin, and alitretinoin |
| etretinate and its metabolite acitretin |
| adapalene, oleyl adapalenate, bexarotene, and tazarotene |
| Trifarotene, seletinoid G |
First generation retinoids are produced naturally in the body and interact with their normal biological counterparts, such as retinol binding protein 4 for retinol, retinoid receptors for all-trans-retinoic acid or 9-cis-retinoic acid. 13-cis retinoic acid has an unknown biological pathway but appears to act as a growth factor.
Second generation retinoids have a mixed effect and interact mainly with signaling in the skin.
Third generation retinoids have narrow biological roles due to their constrained structure, with adapalene mimicking the effects of isotretinoin, bexarotene binding only the retinoid X receptors, and tazarotene binding the retinoic acid receptor beta and retinoic acid receptor gamma forms.
The only fourth generation retinoid, Trifarotene, binds selectively to the RAR-y receptor. It was approved for use in the US in 2019.
All classes of retinoid bind to many proteins. Natural retinoids such as retinol and retinyl esters bind to carrier proteins such as RBP4, and VLDL while synthetic retinoids likely bind to these and other proteins. First generation retinoids are rapidly metabolized by Cytochrome p450 enzymes, typically of the Cyp26 family.
Retinoids provoke rapid elevation of circulating leading to hypertriglyceridemia as well as cholesterol, leading to hypercholesterolemia. Retinoids are further shown to worsen many metabolic diseases, such as diabetes and congestive heart failure. Large-scale randomized, controlled clinical trials have conclusively shown that vitamin A, retinol and other retinoids increase mortality and cancer rates in smokers and asbestos workers. In addition to the harmful effects shared by other retinoids, bexarotene causes severe hypothyroidism.
The Pharmacovigilance Risk Assessment Committee (PRAC), based on its review, confirmed that taking oral retinoids during pregnancy can have harmful effects on the baby as they may cause CNS, cranio-facial, cardiovascular and other defects. The use of acitretin, alitretinoin and isotretinoin should be prohibited in women of childbearing age unless they take measures to prevent pregnancy.
Many lotions that claim to prevent or treat stretch marks contain retinol, which is not an ingredient that is safe for pregnant women. The Association of the American Academy of Dermatology (AAD) recommends that pregnant women consult a health care provider before trying any lotions or oils for stretch mark prevention.
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