Development and characterization of solid lipid microparticles containing vitamin C for topical and cosmetic use

Solid lipid microparticles (SLMs), combined with the advantages of double emulsions (W/O/W) and water-in-oil micro emulsions, are developed for transdermal administration. A modified one-step emulsification method was introduced, which made the industrial production of SLMs easier. Variables involved in preparation that may affect the solubility, stability, and entrapment efficiency of SLMs were investigated. With vitamin C as a model active, the advantages of SLMs in transdermal administration were studied further. Vitamin C, encapsulated by SLMs, exhibited an enhanced storage stability up to 1 month under 25 degrees C and a sustained releasing profile over 24 h. Furthermore, the SLMs was very helpful in delivering vitamin C molecules into skin through stratum corneum. The result showed 5.52-fold (p < 0.05) increased absorption of vitamin C, compared to the vitamin C solution. These studies demonstrate that SLMs could be a promising method for facilitating transdermal penetration of active ingredients with high solubility and low permeability. Practical applications: SLMs could be used as a drug delivery system for hydrophilic active ingredients with low permeability. Experiments have shown better stability and skin permeability of vitamin C incorporated in SLMs when compared with pure vitamin C. Furthermore, the method of producing SLMs is simple and can be realized in a way of industrial production. Since SLMs can dissolve in water, SLMs can be directly used on wet skin with excellent skin-touch feel. As a result, SLMs could be a practical delivery system for hydrophilic compounds with low permeability in many applications such as pharmaceuticals and cosmetics.