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The polyhydroxy acids (PHAs) including the bionic acids (BHAs) represent the next generation of alpha-hydroxyacids (AHAs) for use in cosmetic and dermatologic skin care. Structurally similar to traditional AHAs, the polyhydroxy acids (gluconolactone) and bionic acids (lactobionic acid) provide anti-aging and skin smoothing effects comparable to AHAs, while offering several therapeutic advantages. PHAs are less irritating to skin as compared to AHAs, and cause less stinging and burning. PHA compatibility with clinically sensitive skin types has previously been demonstrated in patients diagnosed with atopic dermatitis and rosacea. PHAs also enhance skin barrier efficiency. These molecules also function as humectants and moisturizers, as well as provide antioxidant-chelation effects due to their polyhydroxy structure. Importantly, tested PHAs do not increase the skin’s potential for sun sensitivity and provide free radical scavenging effects.
PHAs Provide These Key Benefits:
1. Provide Anti-aging Benefits Comparable to AHAs: The PHA acids and lactones have all the known effectiveness of the AHAs in alleviating the signs of dermatological photoaging, while being very gentle. PHA formulations have exhibited strong anti-aging effects including marked improvements in skin clarity (260%, p<0.05) and notable skin plumping (thickening) effects (9.7%, p<0.05). Anti-aging effects have been demonstrated histologically including: increased GAGs, increased viable epidermal thickness and reduced MMP activity. Benefits have been observed on various ethnic skin types including African-American, Asian, Hispanic and Caucasian.
2. Compatible with Clinically Sensitive Skin: The PHA acids and lactones are better tolerated by sensitive skin than traditional AHAs. An open-label evaluation of a PHA (gluconolactone) skincare system was conducted on 30 females with acne rosacea and atopic dermatitis (normally unable to tolerate glycolic acid products). Following 12 weeks of twice daily use, results demonstrated that these PHA products are compatible with these clinically sensitive skin conditions. This gentleness is further supported by the consistently lower scores for PHA creams in the Cumulative Irritation Studies and in sting tests.
3. Combination with Topical Drugs to Enhance Therapeutic Outcomes: PHAs provide therapeutic benefits to skin that are often complementary and additive to the effects of topical drugs. Increased efficacy, improved tolerability and increased cosmetic benefits (skin smoothing) were found when PHA (gluconolactone) was combined with azelaic acid in the treatment of rosacea. PHA can also be used to provide exfoliation benefits and reduce irritation potential of benzoyl peroxide in the treatment of acne. PHAs are compatible with topical retinoid therapy in the treatment of acne and are recommended to be used in combination with topical retinoids to increase moisturization and reduce redness.
4. Barrier Conditioning: The PHA acids and lactones are significantly more barrier conditioning than the classical AHAs such as glycolic and lactic acids. In a double-blind, randomized, complete-block design clinical study, skin was treated twice daily for four weeks with products containing either glycolic acid, gluconolactone, or lactic acid. The skin was challenged with the known skin irritant sodium lauryl sulfate and significantly less damage occurred in the PHA treated sites as compared to damage in the AHA (glycolic and lactic acid) and vehicle treated sites.
5. Water Binding Properties: The PHA acids and lactones are significantly more hygroscopic than the classical AHAs such as glycolic and lactic acids. Humectant studies measuring their respective water attracting and binding properties have shown that lactobionic and gluconolactone have greater water binding and water retention properties than glycolic and lactic acid. Lactobionic acid retains more than 10 times more water that of glycolic or lactic acids and gluconolactone more than 3 times that of glycolic or lactic acid.
6. Antioxidant/Chelating Properties: The PHA acids and lactones are more potent antioxidants than glycolic or lactic acids and comparable to citric acid and ascorbic acid in preventing oxidation of other drug substances. They are also potent chelating agents.
7. Free Radical Scavenging Effect: Bernstein et al demonstrated that gluconolactone provides free radical scavenging effects comparable to other well-known compounds such as ascorbic acid and a-tocopherol using an in vitro model of cutaneous photoaging. This significant benefit was attributed to gluconolactone’s ability to chelate oxidation-promoting metals and possibly via direct free radical scavenging effects of gluconolactone.
8. Sun-Sensitivity: The PHA acids and lactones do not cause sun-sensitivity of the skin as reflected by the production of sunburn cells. In two clinical studies, the skin sites treated for four weeks with either the PHAs gluconolactone or glucoheptonolactone showed no statistically significant increase in the production of sunburn cells following a controlled level of ultraviolet radiation exposure. In contrast, glycolic acid treated sites exhibited a significant increase in sunburn cells following irradiation.