The influence of different mechanical stress on the release properties of HPMC matrix tablets in sucrose-NaCl media

Abstract

Four types of HPMC matrix tablets were studied to investigate the influence of mechanical stress on matrix behaviour using biorelevant in vitro dissolution model, the glass bead device (GBD) and paddle apparatus (USP2), in media with various concentrations of sucrose and NaCl. High or low viscosity grade HPMC was incorporated in the matrix with soluble (lactose) and insoluble (microcrystalline cellulose) diluent. The composition of the tablets and dissolution media were selected based on available literature data, with the intention of providing a sensitive system to reflect differences in hydrodynamics and mechanical stress generated by dissolution apparatuses. Between the GBD and USP2 no substantial differences were demonstrated in low concentration media. The differences were induced in high concentration media; compared to USP2 a higher drug release was observed in GBD for each matrix type. Due to solutes in the media an incoherent gel layer is formed and therefore the matrices are more prone towards the hydrodynamic and mechanical stress of dissolution method, suggesting that motion on the surface of glass beads is an important parameter that affects the removal of the gel layer. In critical media where formation of the functional gel barrier might be compromised, the use of GBD could provide additional insight into the drug release behaviour of the matrix tablet.