Preparation of solid self-emulsifying drug delivery systems using magnesium aluminometasilicates and fluid-bed coating process

Abstract

Solid lipid-based drug delivery systems combine the advantages of solid dosage forms and the solubilizing potential of lipophilic vehicles. In spite of the fact that many methods were proposed for the solidification of liquid lipid formulations, there is no data on the application of the fluid-bed coating technique to impregnate porous pellets, containing magnesium aluminometasilicates with liquid self-emulsifying formulations. Moreover, the functionality of magnesium aluminometasilicates to form porous pellets by the extrusion/spheronization process has not been studied so far.Therefore, the aim of the present work was to determine if magnesium aluminometasilicates could be incorporated into pellets in the extrusion/spheronization process and then to examine if such pellets may be used as solid cores for the conversion of liquid SEDDS into solid SEDDS (S-SEDDS) in the fluid-bed coating process. To achieve these goals, three grades of Neusilin namely SG2, US2 and NS2N were combined with MCC in three wt.% ratios i.e.: 30+70, 50+50, or 70+30. The results showed that the pellets whose matrix was composed of Neusilin SG2 had the highest porosity and the best mechanical resistance. The fluid-bed coating method was found suitable for the impregnation of the placebo pellets with liquid SEDDS, containing ibuprofen as an insoluble model drug. The amount of SEDDS adsorbed on the surface of pellets with silicates was from eight to fourteen times higher as compared to pellets without silicates. The morphology, diameter and circularity of pellets before and after the fluid-bed coating process was examined by scanning electron microscopy (SEM) and the automated particle characterization system (Morphologi G3). The pellets containing Neusilin SG2 had twice as high mechanical resistance as the pellets with Neusilin US2 or Neusilin NS2N, and they were suitable for fluid-bed processing. Dissolution studies showed that from the formulation composed of 70wt.% of Neusilin SG2 after 45min, more than 75% of ibuprofen was dissolved in water and after 30min, more than 80% of ibuprofen was dissolved in the phosphate buffer. Similar results were obtained for S-SEDDS containing 70wt.% of Neusilin US2. The sustained release of ibuprofen was found if 30wt.% of Neusilin US2, 30–50% of Neusilin SG2, or 50–70wt.% of Neusilin NS2N was incorporated into the matrix of pellets.