title: Vitamin A palmitate and α-lipoic acid stability in o/w emulsions for cosmetic application.
abstract: Skin becomes thin, dry, pale, and finely wrinkled with age. Retinoids are a large class of compounds that are important in modern therapy for dermatological treatment of wrinkled skin. Of the retinoids, retinol and vitamin A palmitate are thought to induce thickening of the epidermis and to be effective for treatment of skin diseases. Accordingly, α-lipoic acid or the reduced form, dihydrolipoate, are potent scavengers of hydroxyl radicals, superoxide radicals, peroxyl radicals, singlet oxygen, and nitric oxide with anti-inflammatory properties (1). Cosmetic ingredient stability prediction relies on kinetic quantitative chemical analysis of active components at different temperatures. Vitamin A palmitate and α-lipoic acid, are known to be unstable to light or heat (2). The aims of this study were to evaluate the stability of α-lipoic acid and vitamin A palmitate in the presence of vitamin E (acetate) and other antioxidants in lipophilic/hydrophilic medium (O/W emulsions) at pH 3.0, 5.0, and 7.0. The formulations that were investigated contained 0.12% (w/w) vitamin A palmitate, 0.4% (w/w) vitamin E acetate, and 0.5 % α-lipoic acid (formulation A), supplemented with ascorbyl palmitate, magnesium ascorbyl phosphate, and vitamin C (formulation B) or with butylhydroxytoluene (BHT, formulation C) or ascorbyl palmitate (formulation D). The chemical analyses of α-lipoic acid and vitamin A palmitate were carried out by HPLC. Formulations C and D at pH 7.0 were selected as the most stable for these components. The purpose of this paper is the selection of the most stable formulations for their application in in vivo studies.
authors: Cátedra de Control de Calidad de Medicamentos, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina.
authors: M A
authors: MA
authors: Moyano
authors: A
authors: A
authors: Segall
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003358:Cosmetics; D004224:Diterpenes; D004355:Drug Stability; D004655:Emulsions; D000084562:Retinyl Esters; D013056:Spectrophotometry, Ultraviolet; D008063:Thioctic Acid / Q000737:chemistry*; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D003358:Cosmetics; D004224:Diterpenes; D004655:Emulsions; D000084562:Retinyl Esters; D014801:Vitamin A; C014794:retinol palmitate; D008063:Thioctic Acid