Alpha-hydroxy acids histology and factors influencing penetration

Alpha-hydroxy acids histology and factors influencing penetration 

Unlike single applications, daily use of AHAs seems to thicken the epidermis over time because of the constant stimulation it provides. However, other authors suggest instead a possible thinning of the epidermis in the long term. 

The histological effects of AHAs also reach the dermis. Moy showed that fibroblast cultures in a glycolic environment produced up to 10 times as much hydroxyproKne (a precursor of collagen) than when cultivated in a normal saline environment. A practical problem is that AHAs do not normally reach the dermis (because, apart from Easy Phytic solution, they are neutralized before they can penetrate that far) and therefore cannot directly stimulate fibroblasts as well as they did in this in vitro study. 

In the papillary dermis and sometimes even in the upper reticular dermis, mild edema, an inflammatory reaction and production of new collagen and elastin are observed. Production of these dermal components does not appear to be directly proportional to the extent of the inflammatory reaction. Glycolic acid stimulates fibroblasts to produce collagen, but not in the same way as trichloroacetic acid (TCA) or phenol, which produce a thick horizontal layer of papillary dermal collagen proportional to the dermal injury and hence the repair caused by the acid. However, the laying down of a new layer of collagen in the dermis is one of the 

Other factors also influence the aggressiveness of a glycolic acid solution (Box 7.1). 

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