Porous pellets as drug delivery system

Background: Multiparticulate drug delivery systems, such as pellets, are frequently used as they offer therapeutic advantages over single-unit dosage forms. Aim: Development of porous pellets followed by evaluation of potential drug loading techniques. Method: Porous microcrystalline pellets were manufactured and evaluated as drug delivery system. Pellets consisting of Avicel PH 101 and NaCl (70%, w/w) were prepared by extrusion/spheronization. The NaCl fraction was extracted with water and after drying porous pellets were obtained (33.2% porosity). Immersion of the porous pellets in a 15% and 30% (w/v) metoprolol tartrate solution, ibuprofen impregnation via supercritical fluids and paracetamol layering via fluidized bed coating were evaluated as drug loading techniques. Results: Raman spectroscopy revealed that immersion of the pellets in a drug solution and supercritical fluid impregnation allowed the drug to penetrate into the porous structure of the pellets. The amount of drug incorporated depended on the solubility of the drug in the solvent (water or supercritical CO₂). Drug release from the porous pellets was immediate and primarily controlled by pure diffusion. Conclusion: The technique described in this research work is suitable for the production of porous pellets. Drug loading via immersion the pellets in a drug solution and supercritical fluid impregnation resulted in a drug deposition in the entire pellet in contrast to fluid bed layering where drugs were only deposed on the pellet surface.