Diluents are essential components of a tablet formulation. The type of diluent used in a formulation influences the quality of tablets produced from that formulation. The aim of this study was to evaluate the tableting properties of co-processed excipients (C-PEs) incorporated as diluents in tablet formulation by wet granulation. Metronidazole tablets were prepared by wet granulation incorporating different diluents that were either single component excipients (SCEs) (lactose and

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... e cellulose) or C-PEs (Ludipress®, StarLac®, Prosolv® and AVICEL®HFE). The granules obtained for each formulation were evaluated for particle size analysis, flow properties and compression properties. Tablets weighing 500 mg were compressed from the metronidazole granules on a Single Station Tablet Press using a 12 mm punch and die tooling system. The tablets were kept for 24 h post-production, and the properties of weight uniformity, thickness, tensile strength, friability, disintegration time and dissolution profile evaluated subsequently. Results of granule properties showed that variations in parameters evaluated was as a result of differences in the type and composition of diluent used in formulation. Compactibility and tabletability profile of metronidazole granules revealed a better performance with granules processed with C-PE based diluents compared to SCE-based diluents. Tablets formulated with C-PEs as diluents were uniform in tablet weight, disintegrated faster and yielded a faster drug release compared to tablet formulations containing SCEs as diluent. This study reveals the performance advantage of C-PEs as diluents in tablets manufactured by wet granulation and highlights the importance of rational selection of excipients during tablet formulation.