Development of SLNs from natural lipids: Application to topical delivery of tretinoin

The aim of this investigation was to develop solid lipid nanoparticles (SLNs) from indigenous, natural solid lipids by using a simple microemulsion technique. Furthermore, the aim was to characterize these SLNs and evaluate its potential in the topical delivery of a lipophilic drug, tretinoin (TRN). The developed SLNs were characterized for particle size, polydispersity index, entrapment efficiency of TRN and morphology. TRN-loaded SLN-based topical gels were formulated and the gels were evaluated comparatively with the commercial Product with respect to primary skin irritation, in vitro occlusivity, and skin permeation. The results of the study showed mean particle size < 100 nm of the SLN dispersions with the novel lipids. Up to 46% of drug entrapment in the lipids was attained. Lesser skin irritancy, greater skin tolerance, occlusivity and slow drug release was observed with the developed TRN-loaded SLN-based gels than the commercial product. The research work could be concluded as successful production of SLNs using highly purified stearine fraction of natural solid lipids. The results of the characterization and evaluation established the safety for use, suitability and compatibility of indigenous natural lipids as a novel excipient. (c) 2008 Elsevier B.V. All rights reserved.