Improved photostability, reduced skin permeation and irritation of isotretinoin by solid lipid nanoparticles

The aim of this study was to develop new solid lipid nanoparticles of isotretinoin (IT-SLNs) and evaluate the ability of IT-SLNs to improve photostability, reduce skin permeation and irritating effects. IT-SLNs were prepared by the hot high pressure homogenization method. Size, zeta potential and morphological characteristics of the preparations were assessed by transmission electron microscopy (TEM) and thermotropic properties with differential scanning calorimetry (DSC). IT-SLNs had a small average diameter of 74.05 +/- 8.91 nm and high encapsulation efficiency (EE) of 80.6 +/- 1.2 %. The results showed that the entrapment of IT into SLNs reduced significantly its photodegradation. The in vitro permeation data showed that IT-SLNs can accumulate in the different layers of the skin and prevent systemic uptake of IT in mouse skin. IT-SLNs also significantly increased IT accumulation in the different layers of the stratum corneum of human skin. IT-SLN formulation was significantly less irritating compared to commercial IT-GEL, which shows its potential for improving skin tolerability and being a carrier for topical delivery of IT.