Lateral Spreading of Topically Applied UV Filter Substances Investigated by Tape Stripping

Abstract

The lateral spreading of topically applied substances is a competitive process to the penetration into the stratum corneum (SC). The penetration of topically applied UV filter substances into the human SC and the lateral spreading were investigated in vivo. Tape stripping in combination with spectroscopic measurements was used to study both processes of two UV filter substances. The concentration of both UV filters was determined inside and outside the application area by varying the application and tape stripping protocol. A spreading of the topically applied substances from the treated to the untreated areas was observed, which caused a concentration gradient. This lateral spreading depends on the time between application and tape stripping and the size of the treated skin area. Significant amounts of topically applied substances were found adjoining the application area, due to the lateral spreading which takes place on the skin surface. In general, the lateral spreading must be considered to be a competitive process when studying penetration processes of topically applied substances. It has to be considered during drug treatment of small limited skin areas and for the interpretation of recovery rates obtained in penetration studies.

Metrics and Clinical Relevance of Percutaneous Penetration and Lateral Spreading

“…Meanwhile, the percentage of urea distributed outside the application area was symmetric in this study (fig. 3) - similar to results shown by Jacobi et al [19]. The symmetric surface structure of the skin, consisting of a network of furrows, could be the reason for this result.…”

“…3) show that 18.4% (solution) and 13.4% (cream) of topically applied urea can spread outwards from the application site after 6 h. In addition, the amount of substance found outside the application area seems dependent on the size of the area [19]. Relatively small application areas are usually used so it is important to take lateral spreading into account.…”

“…The recovered amount of urea found 6 h after application of the formulation was reduced, especially on the surface of the treated area, while the amount found on the surface of the untreated skin sites was enhanced. Jacobi et al [19] investigated the lateral spreading of UV filter substances using the same method seen in this present study - tape stripping and spectroscopy. The time between application and tape stripping varied in the protocols, and a time-dependent reduction of the recovered UV filter amount inside the application area was observed.…”

“…Living skin is more flexible and elastic, helping to minimize or avoid disturbances from the typical skin structure. Even a relatively large variation of skin properties in the volunteers measured does not proportionally correlate with the efficacy of lateral spreading [19]. …”

Electron paramagnetic resonance and mass spectrometry: Useful tools to detect ultraviolet light induced skin lesions on a molecular basis – A short review

“…Weigmann et al showed this for the penetration of the drug clobetasol-propionate [64]. The behaviour of sunscreens applied on human skin was investigated using tape stripping, too [65,66]. However, to our knowledge, until now tape stripping in combination with MS was not used for the analysis of UV generated molecular changes within skin with or without sunscreens.…”