The film-forming effect is an important property of formulations for skin improvement and hair protection. Reflectance confocal microscopy, an advanced imaging technique, is an important tool for its evaluation. Thus, the aim of this study was to evaluate the film-forming properties of cosmetic formulations based on starches and containing a Spirulina maxima extract after their application to skin and hair, using sensorial analysis and instrumental measurements, with emphasis on reflectance confocal microscopy. Two formulations based on starches and PEG-75 lanolin containing or not (Vehicle) a Spirulina maxima dry extract were developed. The rheological behavior and sensorial properties of both formulations were evaluated. The film-forming property on the skin was evaluated in terms of skin hydration by RCM imaging analysis and transepidermal water loss (TEWL). The hair tresses were evaluated in terms of mechanical properties and RCM imaging analysis. The formulations showed pseudoplastic behavior and a low hysteresis area. In addition, the presence of Spirulina in the formulation did not interfere in the rheological parameters. Both formulations reduced TEWL and maintained the stratum corneum water content. The protective effect was also observed in the hair, since the application of the formulation with Spirulina showed a better performance in the tensile test when compared to vehicle. Thus, the proposed formulation showed film formation on the skin and hair surface that brought immediate benefits such as a reduction of TEWL. Finally, the formulations were shown to have film-forming effects and their use can be suggested for skin and hair protection against daily damage.
Keywords: film-forming effect; hair treatment; reflectance confocal microscopy; rheology; skin barrier function.
© 2022. The Author(s), under exclusive licence to American Association of Pharmaceutical Scientists.