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SUMMARY POINTS
What’s Important?
UVB exposure and free radicals cause a decrease in collagen production by blocking the TGF-β/SMAD pathway and an increase in breakdown of collagen by increasing matrix metalloproteinases (MMPs). Retinoids block both of these pathways, leading to increased collagen in the skin.
Retinoids are the most proven of any anti-aging ingredients and are FDA approved for photoaging.
Retinoids improve extrinsically and intrinsically aged skin.
Retinol turns into all-trans retinoic acid inside the cell cytoplasm.
Scaling and peeling occur within 2 to 4 days of beginning topical treatment.
Pretreating skin with retinoids 2 weeks prior to a cosmetic procedure speeds wound healing.
Retinoids can, and should, be used in patients who have excessive sun exposure along with antioxidants to protect skin from UV damage and MMPs.
Retinoids are unstable when exposed to air, light, oxidizing agents, high temperature, and low pH.
What’s New?
Retinol has been proven in many studies to reduce fine lines and wrinkles.
Retinoid dermatitis is mediated in part by epidermal derived growth factor.
Genistein can be used to block epidermal-derived growth factor and reduce peeling.
What’s Coming?
Combining retinoids with anti-aging ingredients as discussed in Chapter 37, Anti-Aging Ingredients.
More stable formulations of retinols are in the pipeline.
Retinoid/genistein products are being developed with technologies that promote penetration of genistein.
Trifarotene has not yet been studied for the treatment of photoaged skin, but it is likely that it will demonstrate efficacy.
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A family of compounds derived from vitamin A, retinoids include β-carotene, carotenoids, retinol, tretinoin, tazarotene, trifarotene, and adapalene. For decades retinoids have been used topically and systemically for the treatment of dermatologic disorders, particularly acne, psoriasis, and photoaging. The efficacy of retinoids for the treatment and prevention of photoaging has been proven unequivocally over the last two decades. Understanding the mechanism of action of retinoids on photoaged skin has led to a greater understanding of the etiology of skin aging (see Chapters 5, Intrinsic Aging, and 6, Extrinsic Aging).
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HISTORY OF RETINOIDS IN DERMATOLOGY
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The history of the discovery of retinoids is interesting, lengthy, and very much worth reviewing.1 Retinol is said to have been discovered in 1909, isolated in 1931, and first synthesized in 1947, becoming commercially available soon thereafter.2 Since that time, the retinoid field has proliferated with compounds, now numbering more than 2,500 products.3 In fact, many generic forms of tretinoin are currently available in the United States (U.S.) and retinoids are even combined with medications such as antibiotics and hydroquinone. Topical retinoids were first used in dermatology to treat acne. The first anecdotal evidence that retinoids could improve aged skin was seen in female patients being treated for acne. These patients reported that their skin felt smoother and less wrinkled after treatment.4 This observation was followed by a clinical trial by Albert Kligman, MD, and Jim Leyden, MD, at the University of ...