TFC049 Solid lipid nanoparticles: a study of passive and iontophoretic permeation mechanisms through skin.

Abstract

Solid lipid nanoparticles (SLN) are drug delivery systems developed in the nineties to be an alternative to other colloidal systems like liposomes, emulsions and polymeric nanoparticles. Its use as a drug carrier for topical drug application has been vastly studied for the last years. SLN showed some promising characteristics for this use as the possibility of drug control release, small size, good stability and capacity of protection of the drug encapsulated, besides being less toxic than other drug delivery systems. Meanwhile, despite the large number of studies, there are almost no researches showing how SLN could act to improve drug penetration through the skin. In general, improved drug skin penetration is usually associated with increased hydration of stratum corneum (SC) caused by an adhesive layer (formed by SLN) occluding the skin surface. Furthermore, although intact particles are not normally considered to permeate the horny layer, some studies showed that the follicular pathway may be relevant to drug skin penetration. It is known that the follicular route is the main via of drug penetration when iontophoresis, a physical method that uses a weak electric current to increase skin drugs penetration, is applied. Therefore, iontophoresis of SLN may increase the penetration of intact SLN, increasing the encapsulated drug release inside the skin. SLN marked with hydrophilic and hydrophobic dyes at once may help to elucidate SLN skin penetration in the presence and absence of iontophoresis.