Evaluation of the skin penetration behaviour of sunscreen actives

INTRODUCTION The effectiveness of sunscreens depends on the absorption characteristics of each single UV filter substance. The objective of this study was to determine the penetration profile of UV filter substances using the imaging technique of DermaLab Combo probe and analytical technique of UV/VIS Spectroscopy. MATERIALS AND METHODS 2 mg/cm2 of sunscreen lotion brand Banana Boat SPF 50 PA +++ on of the flexor arms of 10 volunteers. Tape stripping was conducted 30 minutes after the application. After one minute, the strip was then peeled. The videoscope image was taken after each tape strip until 8 tape strips. RESULTS AND DISCUSSION Both results obtained with UV/VIS spectroscopy and videoscope indicate the 1st tape strip contains high concentration of UV-A and UV-B filter compounds. This shows that the removed tape strips consist of the amount of stratum corneum as well as the topically applied substances that are transferred to the tape [1]. The 2nd tape strip has small concentration of topically applied substances of UV-B filters that can relate to less sunscreen distributed within a marked skin area. 3rd tape showed to have lower absorbance value detected and less sunscreen distribution on the skin after tape stripping. There is no significant absorbance detected and measured by UV/VIS spectrophotometer for the fourth until eighth tape strips although there is sunscreen distribution on a marked skin surface. The absorbance of topically applied substances might be reduced if the substances do not distributed homogenously [2]. The data of sunscreen distribution and the absorbance reading are shown in Fig. 1 and Fig. 2, respectively. Fig. 1. Videoscope observation on the distribution of sunscreen on the skin before and after the tape stripping using DermaLab Comb