Stability Assessment of Protein Containing Cosmetic Skincare Formulations

Abstract

The cosmetic company Endue has created a niche cosmetic skincare range containing very expensive therapeutic peptides. Termed ‘cosmeceuticals’ these skincare products topically deliver beneficial, biologically active proteins. There were two aims of this study. The first was to develop analytical methods, for future application, to quantify peptides in formulations. The second was to develop competent methods to assess the stability of cosmetic skincare formulations to provide a Period After Opening, in accordance with new legislation from Europe. Three stability indicating HPLC methods were developed to quantify three different peptides. These methods were developed utilizing similar conditions and equipment to ensure the different peptides could be analyzed without the need for multiple material and equipment purchases. The results gained from these methods provided valuable information on peptide stability, which would aid in formulation and development to maximize potential bioactivity. To assess the stability of the formulations numerous methods were employed. No internationally accepted guidelines exist on how the stability of cosmetics should be determined. The methods used were chosen from an amalgamation of sources, which included; government documents, peer reviewed stability studies and industry guidelines. Together these created a comprehensive stability study comprising; accelerated stability testing, centrifuge testing, package testing, freeze thaw testing and mechanical testing. Parameters that were observed included pH, viscosity, organoleptics and particle size. The stability data obtained was used in conjunction with modified Arrhenius equations to determine a robust Period After Opening for eight different cosmetic formulations. The results pointed out weaknesses in the formulations, provided information on the suitability and compatibility of the packaging and formulations, as well as important information on the stability of the products during transportation.