Water vapor permeation through topical films on a moisture‐releasing skin Model

Abstract

Background Covering the skin by topical films affects the skin hydration and transepidermal water loss (TEWL). In vivo studies to investigate the water vapor permeation through topical films are complicated, expensive, ethically not preferred, and time‐ and labor‐consuming. The objective of this study was to introduce an in vitro and subject‐independent alternative evaluation method to predict the breathability of topical formulations. Methods In this study, we developed an in vitro setup to simulate the TEWL values of human skin and investigated the breathability of five polymeric film formers used in topical formulations. Furthermore, a comparative in vivo TEWL study was performed on ten human volunteers with defined areas of skin covered with films of two selected polymers possessing different barrier properties. Results By employing the in vitro setup, a vinylpyrrolidone/acrylates/lauryl methacrylate copolymer was determined to form the most breathable film, whereas acrylates/octylacrylamide copolymer and shellac films showed the highest barrier properties. The in vivo TEWL study demonstrated the same relative barrier properties for the acrylates/octylacrylamide and polyurethane‐64 films, despite a more complex driving force for water vapor permeation due to moisture accumulation on the covered skin surfaces. Conclusion We obtained a good correlation between the in vitro and in vivo results, demonstrating that our model can categorize different polymeric film formers based on their breathability when applied to human skin. This information can aid in selecting suitable film‐forming polymers for topical formulations with either breathable or occluding functionalities.

In vitro skin model for characterization of sunscreen substantivity upon perspiration

“…The skin‐mimicking substrate consists of four layers, namely a gelatin‐based film, a PMMA film, an adhesive layer and a track‐etched membrane (Figure 1), with each providing specific functionality. The outermost layer is the gelatin‐based film which is responsible for skin‐like properties, for example, surface hydration, water‐responsive behaviour and interaction with topical films [51–54]. The gelatin in this layer is cross‐linked by formaldehyde to improve hydrolytic stability, and glycerol is added as a plasticizer to enhance flexibility [52].…”

Enhancing the sweat resistance of sunscreens

“…The film former assists the uniform distribution of UV filters on the skin and increases the film integrity during contact with water 30–32 . Different categories of film formers are used in sunscreen formulations, including water‐repellent or water‐dispersible materials 32,33 . We selected an acrylic‐based film former with hydrophobic properties and prepared three formulations containing 0%, 0.75%, and 3% of this film forming polymer.…”

“…30 , 31 , 32 Different categories of film formers are used in sunscreen formulations, including water‐repellent or water‐dispersible materials. 32 , 33 We selected an acrylic‐based film former with hydrophobic properties and prepared three formulations containing 0%, 0.75%, and 3% of this film forming polymer. These three formulations were tested on the perspiring skin simulator to assess the effect of the hydrophobic film former and its concentration on the sunscreen substantivity during perspiration.…”

Multifactorial Effects of Gelling Conditions on Mechanical Properties of Skin-Like Gelatin Membranes Intended for In Vitro Experimentation and Artificial Skin Models

“…This method is usually used to study processes involving a considerable number of simultaneously changing variables. The method proposes that the responses resulting from the process (Y) can be expressed as polynomial functions of its variables [ 35 , 36 ]. The responses can be expressed according to Equation (3).…”

“…Another artificial tissue model has been developed by mixing different amounts of gelatin, glycerol, polysaccharides and lipids. The resulting gels were able to mimic the mechanical and surface properties of human skin and were used to study the adhesion of different substrates to skin [ 35 ]. It is clear from the mentioned references that synthesis parameters have cross-dependency effects on the final properties of the resulting materials.…”