Abstract
Two unique pressure-sensitive adhesive (PSA) tapes (PSA-A, -B) with different adhesive properties of commercial PSAs were prepared and evaluated for their usefulness as a pretreatment material prior to the application of transdermal therapeutic systems or topical drug formulations and also as a peeling agent against excess layers of the stratum corneum. In the present study, in vitro permeation experiments were conducted using vertical type diffusion cells and excised hairless rat or porcine skin from which the stratum corneum had been stripped several times with PSAs. The results obtained revealed that PSA-A and -B had higher stripping or peeling effects than those of the marketed PSAs. Marked changes were observed in skin barrier function before and after stripping using PSAs, and the enhancement effect on the skin permeation of drugs achieved by stripping the stratum corneum was markedly different between the PSAs. PSA-A, in particular, markedly improved skin permeation and the skin concentration of topically applied chemical compounds because it removed many layers of the stratum corneum when skin was stripped only a few times. In contrast, when PSA-B was used to pretreat the skin surface, the extent of skin permeation and concentration of drugs was safely increased because only a few layers of the stratum corneum were removed, even with repeated stripping. The enhancement effect achieved by PSA-B was not as high as that by PSA-A. Thus, stripping with PSA-A can be used as a penetration enhancement tool, whereas PSA-B can be used as a peeling material against excess layers of the stratum corneum.
