Glycolic acid peels formulations

A partially neutralized glycohc acid peel formulation refers to the combination of the acid with a base for example, with ammonium hydroxide to yield the salt ammonium glycolate. The pH of this solution is then increased [mean pH is 3.8). 

AHAs are not toxic to melanocytes, and can therefore be applied on dark skins and in all seasons, on condition that effective sun protection is used. Contact time (Table 8.1) depends on skin type, peel concentration and formulation, its pH, the method of application, preliminary skin preparation, etc. At an identical pH, a 50% concentration of glycolic acid will penetrate half as deep as a 70% concentration, and will take twice as long to do so. 

A brief study of the chemistry of the molecules and solutions used in chemical peels immediately questions the hypothesis that acidity is the only basis for the action of peeling solutions. In fact, with the exception of trichloroacetic add (TCA) and non-neutralized glycolic acid solutions, the most commonly used peeling solutions are only weakly acidic, and phenol and resorcinol mixtures may not be acidic at all, having a pH greater than 7 in some formulations. 

Glycolic acid, an AHA, has become one of the most widely used organic carboxylic acids for skin peeling. Glycolic acid formulations include buffered, partially neutralized, and esterified products. Previous studies have recommended the use of a buffered or partially neutralized glycolic acid, which is safer than free glycolic acid. 

Chemical skin peeling with salicylic acid in ethanol or another vehicle may cause adverse effects of a stinging or burning sensation followed by postinflanunatory hyperpigmentation in treated areas. A formulation of 30 % salicylic acid in polyethylene glycol (SA-PEG) was tested in mice and 44 human volunteers [320, 321], It did... 

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