Formulation and quality studies of semi-solid emulsion skin care product containing glycolic acid

Final Master‘s thesis by G. Jaseliunaite „Formulation and quality studies of semi-solid emulsion skin care product containing glycolic acid “. Supervisor Assoc. Prof. Z. Kalveniene; Lithuanian University of Health Sciences, Department of Drug Technologies and Social Pharmacy at the Faculty of Pharmacy. Kaunas, 2020. Aim of the research – To design a stable semi-solid emulsion product used for skincare containing glycolic acid, assess its quality and stability. Objectives of the thesis: To develop a stable semi-solid emulsion system by selecting the compounds and technology; Determine the influence of compounds on the microstructure, texture, and kinetic stability of a semi-solid emulsion system; Assess the qualitative and stability parameters of the semi-solid emulsion system; Determine the effect of different storage conditions on the qualitative indicators of a semi-solid emulsion system. Object of the research – Semi-solid o/w emulsion systems containing glycolic acid. Research methods: spectrophotometry, centrifugation, viscometry, potentiometry, texture analysis, microscopy, stability studies, statistical analysis. Results: Five semi-solid o/w emulsion systems suitable for further research were prepared by modeling the amounts of Damascus rose hydrolate, oils, glycolic acid, emulsifiers, stabilizers, and thickeners. Conclusions: 1) Stable semi-solid o/w emulsion skin care products with glycolic acid were produced, which accounted for 73.4 percent hydrophilic and 26.6 percent lipophilic phases. The technology for the production of a semi-solid emulsion system with the appropriate incorporation of 3 to 6 percent glycolic acid was selected. 2) Semi-solid emulsion systems of all formulations were characterized by kinetic stability. The amount of emulsifier (cetyl alcohol) and the homogenization process were found to reduce the size of the emulsion droplets (strong correlation before homogenization r = - 0.823 and after homogenization r = - 0.857). 3) Viscosimetric studies showed a very strong dependence of the dynamic viscosity on the amount of emulsifier used, r = 0.924. Based on the results of the microscopic examination, a strong inverse correlation was found between the concentration of cetyl alcohol and the diameter of the droplets (r = - 0.857). Texture analysis showed that the oil concentration determines the strength and viscosity index of semi-solid emulsions, and the amount of emulsifier (cetyl alcohol) affects all texture parameters. 4) Stability studies showed that different storage conditions did not affect the quality parameters of semi-solid o/w emulsion systems (p > 0.05). Practical recommendations for future students: In order to produce a homogeneous semi-solid o/w emulsion system of this composition, it is important to follow the production process specified in the thesis. If this work is to be continued, it is advisable to perform microbiological tests and monitor for changes in glycolic acid levels during the stability test