Preparation of co-spray dried cushioning agent containing stearic acid for protecting pellet coatings when compressed

This study investigated the applicability of stearic acid as a co-adjuvant in cushioning agent formulated to prevent coat damage when compressing coated pellets. The co-processed and physical blended fillers were prepared by spray drying and physically blending, respectively, with filler ingredients consisting of stearic acid, microcrystalline cellulose, fully gelatinized starch, and corn starch. Pellets containing drug were produced by coating onto non-pariels a drug layer of metformin followed by a sustained-release layer. Drug release from tablets composed of co-processed or physical blended fillers (0, 1, 5, and 10% stearic acid levels) and coated drug containing pellets were analyzed using similarity factor F2. Under the same force and the stearic acid level, co-processed fillers produced pellet containing tablets which showed higher F2 or t50 values and tensile strengths as well as lower yield pressures as compared with tablets containing physical blended fillers. It was shown that the destructive degree of pellet coating was significantly reduced after being co-processed by homogenization and the incorporation of stearic acid in the cushioning agents, as shown by the improved F2 and t50 values. In addition, disintegrate times of tablets containing co-processed agents decreased despite the hydrophobic stearic acid. In conclusion, the inclusion of stearic acid in co-processed cushioning agents was effective at protecting compacted coated pellets from compression-induced damage without compromising disintegratability. The findings could serve as a step towards resolving the technical challenges of balancing the drug release profiles, tablet tensile strength, and disintegration time of compacting coated pellets into multi-particulate-sustained release tablets.