Improving Flow and Compression of Natural Polymers for Diclofenac SR Tablets via Co-processing with Microcrystalline Cellulose

Abstract

The present study aimed to develop and evaluate sustained-release (SR) tablets of Diclofenac Sodium using co-processed excipients via the direct compression technique. To overcome the poor flow properties of natural polymers, three different co-processed excipients were prepared: Guar Gum with Microcrystalline Cellulose (MCC), Sodium Alginate with MCC, and Xanthan Gum with MCC, each in three distinct ratios. Nine formulations (GM1-GM3, SM1-SM3, XM1-XM3) were compressed into 200 mg tablets and evaluated for pre-and post-compression parameters. All formulations exhibited excellent flow properties and produced tablets with acceptable hardness (5.5-6.5 kg/cm²), low friability (<0.31%), and uniform weight. The in-vitro drug release study over 12 hours revealed that the drug release rate was retarded with an increase in polymer concentration and followed the order: Guar Gum > Sodium Alginate > Xanthan Gum. Kinetic modeling indicated that the drug release best fitted the Korsmeyer-Peppas model, with the release mechanism being anomalous transport, a combination of diffusion and polymer erosion. Among all, formulation XM3, containing Xanthan Gum and MCC in a 2:1 ratio, was identified as the optimized formulation. It demonstrated superior tablet hardness (6.5 kg/cm²), the lowest friability (0.22%), and provided a near-ideal zero-order drug release profile (R²=0.985), achieving 98% drug release in a controlled manner over 12 hours. It was concluded that co-processing Xanthan Gum with MCC produces a robust excipient suitable for directly compressing a highly effective Diclofenac Sodium SR tablet.