For the active care of (photo) aged skin, cosmetically active ingredients that affect the structure of the skin and its biological functions are often used in cosmetics. One such ingredients are proteins and peptides, including whey. Whey is a liquid source of proteins produced by cheese production. In the past it was considered an industrial pollutant, but today it is a well-established ingredient that is incorporated into cosmetic products for skin and hair care due to its beneficial effects on skin and hair as well as on formulation’ features. Whey can be in dry or liquid form and membrane filtration produces whey of different purities - powder, concentrate, isolate, hydrolysate and permeate.
In this thesis, we evaluated the three most optimal shampoo formulations with and without incorporated liquid whey, developed in the framework of previous research at the Department of Pharmaceutical Technology, Faculty of Pharmacy. The aim was to evaluate the potential irritation after application of shampoos with different composition. Shampoo is a cosmetic hair product designed to clean and remove dirt from the hair and scalp, therefore it contains a high concentration of surfactants, which can irritate the skin. Therefore we have also prepared surfactants solutions in different concentrations and ratios to help us interpret the values obtained for the final formulations. We were interested in how these shampoos and solutions affect transepidermal water loss, i.e. the passive loss of water through the intact stratum corneum. The experiment was carried out ion a pig skin model embedded in a Franz diffusion cell in vitro. As part of preliminary testing, the optimal time points for measuring transepidermal water loss after formulation removal were determined. We decided to compare the baseline values with the final values at ten and twenty minutes after removal of the formulations or surfactant solutions.
The basal value before the application of the formulation and the transepidermal water loss value after its removal were measured using a Tewameter®TM 300. A substance is defined as an irritant if the difference between the basal and final value is equal or higher than 6 g/m²/h. All shampoo formulations containing 15 % sodium lauryl sulphate were found to be skin irritants. The results also confirmed that cocamide diethanolamide is a problematic, irritant compound and should therefore be incorporated in cosmetic products at the lowest possible concentration.
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