Loading of tacrolimus containing lipid based drug delivery systems into mesoporous silica for extended release

Abstract

Many studies had been focused on designing tacrolimus sustained release preparations based on solid dispersion technique, but no one had tried to employ mesoporous silica as the carrier material to realize this goal. The purpose of this study was to develop a novel, simple and environmental friendly drug loading method with mesoporous silica to obtain tacrolimus sustained-release preparation. Tacrolimus was firstly dissolved in the molten mixed lipid composed of Compritol 888 ATO and Gelucire 50/13 to prepare a drug loaded lipid-based drug delivery systems (LBDDS), then the liquid LBDDS was adsorbed by mesoporous silica to transfer the liquid into solid powder, ie. the tacrolimus sustained release silica-lipid hybrid (SLH). The SLH was characterized by SEM, CLSM, XRPD and DSC, and the in vitro drug release was tested using a paddle method. SEM and CLSM observation showed that the LBDDS was efficiently distributed throughout the pores of the silica. The results of DSC and XRPD illustrated that the lipid existed inside the silica at amorphous state. The drug-loaded SLH showed good flowability, compressibility, compactibilty and two-phase in vitro drug release process within 24 hours, which did not change obviously even after storage at 40 °C for 10 d. The present study provided a novel and simple method to prepare tacrolimus sustained release powder, which provided a feasible solution to solidify the liquid LBDDS of not only extended drug release behavior, but also improved stability and micromeritic properties.