Release of benzimidazole and benzylidene camphor from topical sunscreen formulations

Drug Dev Ind Pharm. 1999 Dec;25(12):1277-82. doi: 10.1081/ddc-100102299.

Abstract

Absorption of two ultraviolet (UV) filters was evaluated through a lipophilic synthetic membrane (Folioxane) and excised hairless rat skin using a flow-through diffusion cell. Folioxane membrane is an artificial skin used in the treatment of third-degree burns. Diffusion tests were performed with aqueous solutions and galenic formulations (one water-in-oil [W/O] emulsion and two oily gels). Analyses were achieved with high-performance liquid chromatography (HPLC) with UV detection at 295 nm. Diffusion kinetics of 17 beta estradiol, a reference compound, through rat skin, human skin, and Folioxane membrane were performed to validate the in vitro model. Phenylbenzimidazole and methylbenzylidene camphor in aqueous solutions were diffused at a regular rate through the Folioxane film. The release of phenylbenzimidazole was very slow, whereas the release of benzylidene camphor was more pronounced: a decrease of the quantity was observed in the donor compartment (30% at 6 hr and 93% after 72 hr). A significant flow of benzylidene camphor was also measured through excised skin of rat in the first 3 hr. The skin absorption was 38% over 72 hr. The W/O emulsion had low penetration of UV filter: 20% of the initial amount for Folioxane membrane and 0.4% for rat skin. In contrast, the penetration of two oily gels was identical: 28% on Folioxane membrane and 0.6% on rat skin. This study demonstrates the transcutaneous diffusion of two important classes of sunscreens through a lipophilic Folioxane membrane and through excised hairless rat skin. From the results, Folioxane membrane appears to be an alternative model for studying diffusion of topical molecules and as a tool for guiding formulation choices.

Publication types

  • Comparative Study

MeSH terms

  • Administration, Topical
  • Animals
  • Benzimidazoles / pharmacokinetics*
  • Benzylidene Compounds / pharmacokinetics*
  • Camphor / pharmacokinetics
  • Diffusion
  • Emulsions
  • Estradiol / pharmacokinetics
  • Gels
  • Humans
  • Membranes, Artificial*
  • Rats
  • Reproducibility of Results
  • Skin Absorption*
  • Sunscreening Agents / pharmacokinetics*

Substances

  • Benzimidazoles
  • Benzylidene Compounds
  • Emulsions
  • Gels
  • Membranes, Artificial
  • Sunscreening Agents
  • Estradiol
  • Camphor