Photo: Tretinoin treatments, courtesy Drugs.com.
According to Dr. David E. Bank, director of the Center for Dermatology, Cosmetic & Laser Surgery, researchers discovered the anti-aging properties of Retin-A, a prescription topical treatment containing a derivative of vitamin A, in 1985, when it was first used as an acne treatment. Patients reported decrease in the appearance of wrinkles and smoother skin, in addition to a reduction in acne.
The active ingredient in Retin-A, tretinoin (brand name Renova), is the only chemical to date to receive FDA approval for anti-aging and anti-sun damage properties. According to research by Fisher et. al cited by Dr. Leslie Baumann in Cosmetic Dermatology, retinoids are effective in preventing and treating the collagen loss caused by photodamage. UV exposure decreases collagen types I and III with 24 hours, but treatment of the skin with all-trans retinoic acid prevents the loss of these types of collagen synthesis. In addition, Fisher et. al demonstrated that application of tretinoin inhibits the induction of matrix metalloproteinase genes (more here), which are in part responsiblefor collagen degradation.
Side effects of retinol include skin irritation, desquamation, and redness. In addition, use of vitamin A derivatives has been associated with birth defects, and so it is advisable for women who are pregnant, breast-feeding, or those who may become pregnant to avoid use of tretinoin, retinol, or retinyl palmitate. It is further notable that patients with sensitive skin should use lower concentrations of tretinoin (0.025% rather than 0.1%) or, alternatively, lower concentrations of different metabolites of vitamin A, namely retinol or retinyl palmitate. According to Dr. Baumann, retinol and retinyl palmitate should be present in concentrations of at least 0.04% to 0.07% and packaged properly (to avoid oxidation) in order to be effective, as they are in Neutrogena Healthy Skin with SPF 20 ($19.99, Drugstore.com) and Roc Retinol Actif-pur ($16.99, Drugstore.com).
So how are retinol and retinyl palmitate related to the proven-effective tretinoin? According to Dr. Baumann, retinol is classified as a cosmetic rather than a drug because it must first be converted to retinaldehyde, and then all-trans retinoic acid within the skin in order to be effective. In general, retinol is considered to be about 20 times less potent than retinoic acid, and thus higher concentrations of retinol need to be used to achieve similar efficacy to all-trans retinoic acid (i.e., 0.04% or 0.07% versus 0.025%). However, although retinol needs to be present in higher quantities than tretinoin in order to be effective, patients typically experience lower levels of irritation using retinol products. Similarly, retinyl palmitate is a combination of pure retinol and palmitic acid (a substance typically used in cosmetics as a cleansing agent), and so it too must be converted to retinaldehyde and then all-trans retinoic acid within the skin in order to be effective. However, when present in sufficiently high concentrations, retinyl palmitate displays results similar to that of retinol. One caveat: based on information from Dr. Baumann’s site, make-up products with retinol will expire approximately one month after opening, so use accordingly.
Tretinoin itself is available in five prescription formulas: Retin-A Micro (Johnson & Johnson), Renova (Johnson & Johnson), Avita, Differin (Galderma), and Tazorac (Allergan). According to Dr. Bank, Retin-A Micro uses microsphere technology to allow a more sustained release of tretinoin over time. Some patients may find Retin-A Micro drying, in which case Renova, a product with tretinoin delivered in a mineral-oil base, may be recommended. A third option, Avita, is considered to be less irritating than Retin-A Micro, but without the mineral-oil base that can stimulate acne in some patients. The fourth option, Differin, contains a different chemical, adapalene, and is considered to make skin less photo-sensitive than other tretinoin products. Lastly, the newest product, Tazorac, contains tazarotene, and may be drying, but was approved by the FDA in 1997 for the treatment of acne. According to Dr. Baumann, a 2000 study by Kakita et. al found that the efficacy of tazarotene 0.1% gel is clinically comparable to 0.1% tretinoin [in Retin-A Micro] and 0.025% gel tretinoin[Renova] and adapalene 0.1% gel [Differin].
Vitamin-A derivatives are thereby considered to be excellent prevention and treatment against the signs of aging caused by ultraviolet rays. However, the effects of vitamin A derivatives on sensitive skin can be harsh. As such, provided one is not breast-feeding, pregnant, or may become pregnant, s/he should talk to their dermatologist about making the right choice of tretinoin, retinol, or retinyl palmitate for a part of their anti-aging routine on a daily basis.