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Polyhydroxy Acids
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Polyhydroxy acids (PHA) are a special type of AHA (alpha
hydroxyacid) known to modulate
keratinization, normalize stratum corneum exfoliation and thickness, and condition the barrier integrity due to the effects mediated by the alpha hydroxy group. In addition, polyhydroxy acids are thought to penetrate the skin more gently than traditional AHAs due in part to their larger size and multiple hydroxyls resulting in minimal or no subjective discomfort when applied topically. For this reason, PHAs offer a distinct advantage over conventional AHAs (glycolic acid and lactic acid) when used on sensitive skin, such as
rosacea, atopic dermatitis, eczema, seborrhea and in hyperkeratosis associated with psoriasis,
ichthyosis, and keratosis pilaris. Due to the additional hydroxyl groups, PHAs
appear to attract more water through hydrogen bonding, and therefore provides enhanced moisturization to the skin. In fact, many PHAs are strong humectants that can attract and bind atmospheric water. Many polyhydroxy acid salts including that of
gluconolactone, glucoheptonolactone, glucoheptonate (also known as
gluceptate) and lactobionic acid, are used as counter ions to deliver IV and oral nutritional agents and
medicinals. Many polyhydroxy acids including
gluconolactone, lactobionic acid and glucoheptonolactone have also been shown to function as antioxidants through chelation of oxidation promoting metals and thus can inhibit the oxidation of other food and drug substances and this property may prove beneficial in the prevention of
photoaging.
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Amphoteric Complexes
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A patented controlled-release formulation technology by NeoStrata to impart enhanced gentleness to AHA products through reduced stinging and irritation potential on sensitive skin. These formulations contain an alpha or polyhydroxy acid and a complexing substance such as amphoteric amino acids including
arginine, glycine or lysine. When these formulations are prepared properly, a temporary molecular complex is formed between the AHA or PHA and the amino acid through ionic/ionic, dipole/ionic and dipole/dipole attracting forces so that, over time, the AHA is slowly released to the skin surface. This controlled-release formulation has been found to be bioequivialent and therapeutically equivalent to
non-amphoteric AHA and PHA formulations. There is, however, a reduction of irritation and negative sensory effects including stinging and burning with the amphoteric formulations.
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