(105f) Compressed Fluid Based Process for Development of Cosmetic Products

Many aesthetic and functional problems of skin, such as cutaneous dryness and atopical dermatitis, are due to reduced amount of lipids in the external skin layer. These diseases can be resolved by using topical creams containing balanced mixtures of epidermal lipids. However, the set up of a suitable process for obtaining epidermal lipid based formulations represents a key step to yield an effective topical systems. Actually, the production process must prevent material degradation, avoid the use of organic solvents and yield products with the desired properties. In this regard, we recently investigated the epidermal lipids processing by compressed gas to obtain solid lipid nanoparticles. Particles from Gas Saturated Solution process (PGSS) was used. PGSS is a flexible solvent free techniques which operate under mild conditions and can be properly adapted to the aim of the work. The lipid mixture processed by PGSS is melted under CO₂ saturation and atomized through a special nozzle. In the present study, various epidermal lipid mixtures were selected according their functional and physicochemical properties. Preliminary Differential Scanning Calorimetric (DSC) investigations were carried out to evaluate the melting point of the mixtures, which is an important parameter for the process design. Runs were carried out using different formulation compositions and processing conditions. The effects of the operative variables, such as operative temperature and pressure and air flow, were investigated to obtain nanometric particles with optimal lipid composition. The nanoparticles were characterized by Photon Correlation Spectroscopy (PCS) and DSC to determine their mean and distribution size. Melting temperature and enthalpy with relative polymorphic configurations were also evaluated. The particle mean size was in the range of 200-500 nm. These lipid nanoparticles were formulated as cream-gel systems, which were produced using simple lipid based formulations or polymer/silicone emulsions. These systems were analyzed by optical microscopy and rheological techniques to study the effect of the nanoparticle concentration on the structure, spreadability and functionality of the final product. The cream formulations presented good microstructure (regular with droplets of about 2-5 μm) and were stable throughout 3 months investigation.