Evaluation of novel soya-lecithin formulations for dermal use containing ketoprofen as a model drug

In this study soya-lecithin aggregates, prepared by a technique using compressed gas, are used to formulate new dermal preparations. Ketoprofen (KP), a nonsteroidal anti-inflammatory drug (NSAID) is included as a model drug. The technique offers the possibility of incorporating auxiliary agents, such as penetration enhancers, anti-irritants and moisturisers together with the drug in one process. Apparent partition coefficients for n-octanol-phosphate buffer were determined for each of the lecithin aggregates. In general, soya-lecithin improves the partition of KP into n-octanol. The resulting products were included in widely used hydrophilic and hydrophobic vehicles. After 24 h, the cumulative amount of drug released through an artificial membrane was higher from the hydrophilic gels (2.6-4.3 mg) and the hydrophobic creams (0.23-0.392 mg) than from the control preparations (control hydrogel: 1.3 mg; control hydrophobic cream: 0.141 mg). However, the cumulative amount released from the hydrophobic vehicles was generally lower than from the hydrophilic matrices. Cumulative amounts such as those released from the hydrophilic preparations can also be achieved using supersaturated formulations based solely on the drug-loaded lecithin aggregates and a suitable oily component (4.07 mg). Results from the diffusion studies using artificial membranes were confirmed by permeation studies using excised rat skin. The improvement in skin permeation is related to both the solubilising effect of the lecithin matrix and the penetration enhancing effect of lecithin itself. The novel soya-lecithin aggregates are promising candidates for new drug delivery systems in dermatology and cosmetology. Lecithin aggregates loaded with drugs are multifunctional carriers that also act as penetration enhancers.