Alpha hydroxy acids (AHA’s) have been described in the literature for the treatment of a number of conditions in which abnormal keratinization consistently contributes to pathogenesis. These include use of glycolic peel for acne scars. An study performed by Tung RC et al evaluated the efficacy and skin tolerance of the alpha hydroxy acid gluconolactone 14% in solution for acne treatment when compared with its vehicle (placebo) and 5% benzoyl peroxide lotion. The results of this study showed that both AHA’s and benzoyl peroxide had a significant effect in treatment of acne by reducing the number of lesions (inflamed and non-inflamed). Furthermore, fewer side-effects were experienced by acne patients treated with AHA’s in comparison with benzoyl peroxide.
Mechanism of action, how AHA’s work:
Alpha hydroxy acids are botanical substances that induce mild inflammation and accelerate exfoliation with little or no burning or stinging, said Paul Lazar, MD, emeritus clinical professor of dermatology at Northwestern University Medical School, Chicago, Ill. “A little inflammation isn’t bad. Alpha hydroxy acids improve skin coloring and even skin tone,” said Lazar, who served for many years as director of the American Medical Association’s Committee on Cosmetics and Cutaneous Health. “A little edema,” he noted, “puffs out fine wrinkles.” Also effective as an acne treatment. But concerns remain, he said, about whether chronic low-grade irritation has adverse lasting effects, such as increasing blood vessel dilation, whether the alpha hydroxy acids harm the skin’s barrier functions, and how much they increase sun sensitivity.
The most widely used of these chemicals are the alpha-hydroxy acids (AHAs). Beta-hydroxy acid, better known as salicylic acid, long a part of the dermatologist’s acne treatment armamentarium, is a newer addition to cosmetic products, as are combination-hydroxy acids and poly-hydroxy acids.
The concentration of hydroxy acids in a product is directly related to its potential to cause peeling and irritation, said Zoe Draelos, MD, clinical associate professor of dermatology . But concentration is not the only factor, she said, as preparations can be changed by buffering or through neutralization. Low concentrations, such as 1% AHAs, have been shown to alter the pH of the outer 3 layers of the stratum corneum, she said, while the higher concentrations available in some cosmetic products, such as 10% AHAs, have been shown to affect the pH of the stratum corneum 10 to 20 layers deep and have been used in formulations for acne scars. Application of a glycolic acid lotion to the skin, she said, has been reported to yield a 2.4% concentration in the stratum corneum, an 11.6% concentration in the epidermis, and an 8.6% concentration in the dermis. “This degree of biological activity,” she said, “does not fit with the current definition of cosmetics”. (Skin Aging. 1998;6:45-47).
The safety of glycolic acid and other AHA ingredients has been investigated by the Cosmetic Ingredient Review Board, an independent panel of physicians and other scientists with no financial ties to the cosmetic industry, for the Cosmetic, Toiletry, and Fragrance Association (CTFA), the industry’s trade organization in Washington, DC. The review board concluded that AHAs were safe for use by consumers at a concentration less than 10% and at a pH of 3.5 or greater, and also for brief, discontinuous use in salons when applied by trained professionals in a concentration no greater than 30% and at a pH of no less than 3.0, followed by thorough rinsing of the skin. The reviewers did not examine the medical uses of AHAs at higher concentrations.
The review board also found that use of AHAs increased sun sensitivity by 13% overall but in some persons by as much as 50%, a finding that raises concern about accelerated photoaging and elevated risk of skin cancer. The reviewers, said Gerald McEwen, PhD, CTFA vice president for science, concluded that formulating some products differently adding a sunscreen with a sun protection factor of 2, for example could eliminate the added sun sensitivity. They also recommended that people who use these preparations be advised to use daily sun protection, including sunscreens and protective clothing (Int J Toxicol. In press).
The FDA, according to Bailey, “is not as convinced as the industry that the problem can be solved this easily.” The FDA has referred AHAs to the National Toxicology Program for a study of phototoxicity, a process that will take several years. The same concerns about possible long-term effects apply to beta-hydroxy and other hydroxy acid products with frequent use in anti aging skin care. In the meantime the FDA may provide guidelines to the industry or regulations for safe use but has not yet made a decision on this matter.
Even though certain AHA’s formulations can bring glow, smoothness and tone to your skin and have been used in anti aging serum formulations, the renewed AHA’s -underwent skin appear to be in need of more care. This care includes use of mositurizers and suncreens. The final word is the beauty and youthfulness associated with use of AHA’s cost more than its primary value. To be on the safe side:
Do not use AHA’s products containing more than 8% AHA’s during the day
Wear a moisturizer and a sunblock during the day while using a AHA’s formulation with more than 8% AHA’s at night