Evaluating the UVA photoprotection of sunscreens with murine skin edema.
The acute and chronic deleterious effects of UVA on skin have prompted a growing interest in developing effective UVA-photoprotective sunscreens. The quantification of their UVA photoprotection remains, however, a major problem. In the present study, murine skin edema induced by 8-methoxypsoralen plus UVA (PUVA) is evaluated as a screening method for quantifying the UVA photoprotection of commercially available sunscreens. The PUVA-induced murine skin edema is provoked on the dorsa of female hairless albino mice and measured with a hand-held micrometer. A clear time course and a well-defined dose-response relationship are demonstrated. Therefore, a UVA-photoprotection factor (UVA-PF) could be defined by dividing the minimal edema dose with sunscreen by the minimal edema dose without sunscreen. The UVA-PF values obtained with this method were quantitatively and qualitatively very similar to those obtained in 8-methoxypsoralen-photosensitized murine skin by using the number of sunburn cells as the biologic end point and were qualitatively similar to UVA-PF values obtained in human skin using phototoxic erythema and UVASUN-induced tanning as the parameter. It is concluded that PUVA-induced murine skin edema offers an objective, reproducible, and easily applicable screening method for quantifying the degree of UVA photoprotection of a sunscreen.
Garmyn
M
M
Photodermatology Unit, University of Leuven, Belgium.
Roelandts
R
R
D000818:Animals; D004487:Edema / Q000188:drug therapy* / Q000209:etiology; D005069:Evaluation Studies as Topic; D051379:Mice; D011701:PUVA Therapy; D012867:Skin / Q000528:radiation effects*; D012871:Skin Diseases / Q000188:drug therapy* / Q000209:etiology; D012885:Skinfold Thickness; D013473:Sunscreening Agents / Q000627:therapeutic use*; D014466:Ultraviolet Rays
D013473:Sunscreening Agents