Triptolide loaded solid lipid nanoparticle hydrogel for topical application.

Triptolide (TP) has been shown to have anti-inflammatory, antifertility, antineoplastic, and immunosuppressive activity. However, its clinical usage is limited to some extent due to its poor water solubility and toxicity. In order to use innovative ways to administer TP and to overcome or alleviate its disadvantages, controlled-release delivery systems such as solid lipid nanoparticle(SLN(s)) have been developed. In the present paper we describe the preparation and some characterization of specialized delivery systems for TP. The transdermal delivery and anti-inflammatory activity were also evaluated. The results indicated that SLN could serve as an efficient promoter of TP penetrating into skin. Furthermore, different formulations were optimized in this study. The best formulation of SLN, consisted of tristearin glyceride, soybean lecithin, and PEG400MS, with a particle size of 123+/-0.9 nm, polydispersity index (PI) of 0.19, and zeta potential of -45 mV. When this SLN dispersion was incorporated into hydrogel, the nanoparticulate structure was maintained, and aggregation and gel phenomena of the particle could be avoided. The cumulative transdermal absorption rate in 12 h was 73.5%, whereas the conventional TP hydrogel was 45.3%. The anti-inflammatory effect is over two-fold higher than that of conventional TP hydrogel. Moreover, this SLN hydrogel consists of pharmaceutically acceptable ingredients, such as soybean lecithin and lipid, and the nanoparticle can improve safety and minimize the toxicity induced by TP.