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Compaction analysis and optimisation of convex-faced pharmaceutical tablets using numerical techniquesCapping failure, edge chipping, and non-uniform mechanical properties of convexfaced pharmaceutical tablets are common problems in pharma industry. In this paper, Finite Element Modelling (FEM) and Design of Experiment (DoE) techniques are adopted to find the optimal shape of convex-faced (CF) pharmaceutical tablet which has more uniform mechanical properties and less capping and chipping tendency. The effects of the geometrical parameters and friction on the compaction responses of convex-faced pharmaceutical tablets were first identified and analysed. The finite element model of the tabletting process was generated using the implicit code (ABAQUS) and validated against experimental measurements. Response Surface Methodology (RSM) was employed to establish the relationship between the design variables, represented by the geometrical parameters and the friction coefficient, and compaction responses of interest including residual die pressure, the variation of relative density within the tablet, and the relative shear stress of the edge of the tablet. A statistical-based optimisation approach is then employed to undertake shape optimisation of CF tablets. The obtained results demonstrated how the geometrical parameters of CF tablet and the friction coefficient have significant effects on the compaction behaviour and quality of the pharmaceutical tablet.
Improved tableting behavior of paracetamol in the presence of polyvinylpyrrolidone additive: Effect of mixing conditionsMonoclinic paracetamol (PA) is notorious as a poorly compactible model drug. Polyvinylpyrrolidone (PVP) is a polymer that can act as an effective binder to improve the mechanical properties of PA. It is surprising however that the role of mixing conditions on the physicochemical and mechanical properties of PA–PVP mixtures has not been reported previously. The results of this work showed that PA–PVP mixtures containing 5% (w/w) PVP prepared using high energy mixing conditions had considerably smaller particle size distributions and higher cohesivities than mixtures prepared using low energy mixing conditions. Solid-state analysis did not detect any change in the monoclinic crystalline form of PA after mixing with PVP. The following rank order of tabletability for PA–PVP mixtures was obtained according to the mixing condition: low shear ∼ medium shear < dry high shear < wet high shear < high-speed homogenization. A higher level of hydrogen bonding was detected in the mixtures prepared via high energy mixing conditions than in those prepared using low energy mixing conditions. Mixing is therefore a critical process that needs to be optimized during the preparation of interactive mixtures for tableting.