Porous magnesium aluminometasilicate tablets as carrier of a cyclosporine self-emulsifying formulation

The aim of this study was to investigate the ability of liquid loadable tablets (LLT) to be loaded with a self-microemulsifying drug delivery system (SMEDDS) containing cyclosporine (CyA). LLT were prepared by direct compression of the porous carrier magnesium aluminometasilicate and subsequently loaded with SMEDDS by a simple absorption method. SMEDDS was evaluated regarding visual appearance and droplet size distribution after dispersion in aqueous media. The developed SMEDDS was found to be similar to Neoral. LLT were characterized before and after loading regarding weight variation, tablet hardness, disintegration time, and in vitro drug release. It was found that LLT with high porosities suitable for liquid loading and further processing could be prepared. Adding a tablet disintegrant was found to improve in vitro drug release. Additionally, the volume-based loading capacity of LLT was evaluated and found to be comparable to soft gelatin and hard two-piece capsules. Furthermore, the pharmacokinetic performance of CyA from loaded LLT was tested in two PK-studies in dogs. Absorption of CyA from SMEDDS loaded into LLT was found in the first study to be significantly lower than the absorption of CyA from SMEDDS filled into a capsule. However, addition of a superdisintegrant improved the absorption markedly. The bioavailability of CyA from SMEDDS loaded into disintegrating LLT was found in the second study to be at the same level as from capsule formulation. In conclusion, the LLT technology is therefore seen as a promising alternative way of achieving a solid dosage form from liquid drug delivery systems.