Algorithm for in vitro Sun Protection Factor based on transmission spectrum measurement with concomitant evaluation of photostability.
In the in vitro evaluation of Sun Protection Factor (SPF), the photostability of the ultraviolet (UV) filters can have a major impact, especially for high-SPF formulations, but is generally not taken into consideration. In this study, we present a UV transmission spectrum measurement system utilizing a high-sensitivity UV photomultiplier tube with concomitant evaluation of photostability. We have developed an algorithm to estimate SPF in vitro by converting the amount of UV light transmission through the sunscreen layer into cumulative relative erythema effectiveness to obtain one minimal erythema dose. Thus, the algorithm uses the same endpoint as in vivo SPF methods, but with a photomultiplier tube as the detector instead of skin. The values obtained showed an excellent correlation with in vivo SPF values, even for high-SPF sunscreens exceeding SPF 50. This method should be suitable as an in vitro SPF testing method for regulatory purposes.
Miura
Yoshimasa
Y
Shiseido Research Center, Yokohama-shi, Japan. yoshimasa.miura@to.shiseido.co.jp
Takiguchi
Yoshihiro
Y
Shirao
Masayuki
M
Takata
Sadaki
S
Yanagida
Takeshi
T
Fukui
Hiroshi
H
Naganuma
Masako
M
Hatao
Masato
M
D000465:Algorithms; D055668:Photochemical Processes / Q000528:radiation effects*; D012867:Skin / Q000187:drug effects / Q000528:radiation effects*; D013057:Spectrum Analysis; D013472:Sunlight; D013473:Sunscreening Agents / Q000494:pharmacology
D013473:Sunscreening Agents