Stability of cosmetic formulations containing esters of vitamins E and A: chemical and physical aspects.

Cosmetic stability prediction relies on quantitative chemical determinations of active components after certain times and in different temperatures. However, physical stability, an important parameter in skin care products is not considered in these conditions. This study proposes the determination of cosmetic stability chemical and physical parameters validated by (HPLC) chromatography and rheological measurements, respectively, using a gel-cream containing retinyl palmitate and tocopheryl acetate as a model system. The predicted shelf life addresses both the physical and chemical aspects of the system. Results emphasize the importance of studying both parameters by showing the relation of components degradation and physical stability. Moreover, they contribute to an improved understanding of physical and chemical stability aspects of cosmetic formulations, mainly if they contain Vitamins A and E derivatives.