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 system. 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 Particles from Gas Saturated Solution technique (PGSS) to obtain solid lipid nanoparticles. PGSS is a flexible solvent free technique that operates under mild conditions. In this process, the lipid mixture processed is melted under CO2, saturated and atomized through a special nozzle in a semi-continuous apparatus. Preliminary Differential Scanning Calorimetric (DSC) investigations were carried out to evaluate the melting point of the various epidermal lipid mixtures (Ceramide, Cholesterol and Radiacid), which is an important parameter for process design. Then, micronization runs were performed using different formulations and processing conditions. The effects of the operative variables, such as operative temperature and pressure, were investigated to obtain nanometric particles with optimal lipid composition. Photon Correlation Spectroscopy (PCS) analysis showed that the particle mean size was in the range of 200-500 nm. Melting temperature and enthalpy were evaluated by DSC. The lipid nanoparticles obtained were finally 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 of investigation.