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Effects of Topically
Applied Glycolic Acid (GA) on the Sensitivity of Human Skin to UV-Induced
Damage
Kaidbey, Kais1,
Sutherland, Betsy2, Dennis, Donna3,
Wamer, Wayne3, Barton, Curtis3
and Kornhauser, Andrija 3
Ivy Laboratories, Philadelphia, PA1
Brookhaven Natl. Laboratories, Upton, NY2
Food & Drug Administration, Washington, DC3
Food & Drug Administration, Washington, DC4
Food & Drug Administration, Washington, DC5
Food & Drug Administration, Washington, DC6
Abstract-
Glycolic acid (GA)is used widely in a large number of cosmetics products
for daily use over long periods of time. Its application has dramatically
increased in the last decade. This study was conducted to investigate
the effects of GA, applied in a cosmetic formulation, in modifying UV-sensitivity,
and to determine whether the effect was reversible after discontinuing
GA applications. 29 healthy subjects of both sexes (skin type I-III)
were recruited. The subjects were divided into two groups: in group
1 (n=16), photosensitivity was evaluated by determination of sunburn
cells (SBC's) and the minimal erythema dose (MED); in group 2,
(n=13) cyclobutyl-pyrimidine dimers (CPD's) were evaluated. The
test material consisted of 10% GA, pH 3.5, in a cosmetic formulation
(vehicle). The material and vehicle were applied to rectangular areas
over the mid-back region daily (6x per week), for 4 consecutive weeks.
An additional area served as an untreated control. At the end of treatment,
a single dose of 1.5 MED of UVB was delivered to treated and untreated
sites on all subjects. Shave biopsies were obtained 24 hrs after UV
exposure in group 1 for enumeration of SBC's, and immediately after
UV exposure in group 2 for determination of CPD's. In addition,
in group one, at the end of the 4 week treatment period, and again one
week later, the MED was determined in each treated and control area.
Treatment with GA resulted in a 18% reduction in MED, as compared to
the vehicle treated sites, and an increase in number of SBC's by
a factor of 1.9. These changes induced by GA were statistically significant.
The CPD's were elevated but not to a statistically significant
level. The MED and the number of SBC's returned to control values
after one week of termination of treatments. In conclusion, topical
application of GA sensitizes the skin to the damaging effects of UVB
and this process is reversible.
Keywords: glycolic
acid, UV damage, sunburn cells, human study
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