Effect of compression process parameters on the physical properties and in vitro release mechanism of the press-coated nifedipine matrix sustained-release tablets

We aim to clarify the influence of compression process parameters on the physical properties and release kinetics of the dual-reservoir press-coated tablets (PCTs). The critical compression force from plastic deformation to elastic deformation was 12.15 and 20.08 kN for core tablets and coat layer powder, respectively. Below 12.15 kN, the core tablets underwent flattening, further compression and surface area changing during the compression process of the coat layer, which in turn made the coat layer further compressed in both axial and radial space, resulting in reduced porosity and increased tensile strength. The release testing revealed that PCTs exhibited a dual-reservoir sequence release mechanism of super case II transport in the coat layer and irregular transport in the core tablets, with compression force of the core tablets as a crucial process parameter. In brief, release profiles could be designed by adjusting drug distribution in dual-reservoir and process parameter of PCTs.