[Structure of cholesterol-containing creams].
The colloidal structure of a four-component system consisting of cholesterol, fatty alcohol, petrolatum and water was studied. Depending on the variation of temperature, chain length of the fatty alcohol and concentration of all components, creamy systems of w/o type could be prepared, which present different structural features. Liquid phases as well as crystalline and/or liquid crystalline phases participate in the structure of the creams. The liquid phases are represented by water and by liquid hydrocarbons of low molecular weight of petrolatum. Part of the surfactants is dissolved in this latter phase. The liquid crystalline phase is formed by cholesterol and fatty alcohol together. The characterization of the lamellar liquid crystalline phase was performed by polarized light microscopy and small angle x-ray diffraction. The formation of the lamellar liquid crystals is favoured in a certain molar concentration range of cholesterol and fatty alcohol. The liquid crystalline region is largest with tetradecanol. The lamellar liquid crystals swell with water up to a certain limit. This incorporation of water stabilizes the lamellar liquid crystals so that they are stable in a larger temperature range. The crystalline structures form a network consisting of solid hydrocarbons and the eutectic mixture of cholesterol and fatty alcohol. If water is present the surfactants crystallize as hydrates. A surplus of water can be dispersed as droplets mechanically. Referring to maximum capacity of water incorporation, systems with lowest crystalline amounts (only the network of petrolatum) were best. The surfactants should be completely dissolved.
D002626:Chemistry, Pharmaceutical; D002784:Cholesterol / Q000032:analysis*; D004055:Differential Thermal Analysis; D005233:Fatty Alcohols / Q000032:analysis; D007700:Kinetics; D009824:Ointments; D010577:Petrolatum; D014961:X-Ray Diffraction
D005233:Fatty Alcohols; D009824:Ointments; D010577:Petrolatum; D002784:Cholesterol
Strukturuntersuchungen an cholesterolhaltigen Cremes.