Synthesis, characterization and evaluation of deacetylated xanthan derivatives as new excipients in the formulation of chitosan-based polyelectrolytes for the sustained release of tramadol

This paper addressed the application of deacetylated xanthan (XGDS) and chitosan (CTS) as a mixture blend forming hydrophilic matrices for Tramadol (TD) sustained release tablets. XGDSs derivatives were obtained by alkaline treatment of xanthan gum (XG) with various degrees of deacetylation (DD). The obtained products were characterized in terms of structural, thermal and physicochemical properties. Different tablet formulations containing CTS/XGDSs were prepared by direct compression method and compared to CTS/XG tablets. Flow properties of powder mixtures and pharmaceutical characteristics were evaluated. The dissolution test of TD was realized under simulated gastric and intestinal conditions to achieve drug release more than 24 h. All developed tablets were found conforming to standard evaluation tests. It was shown that CTS/XGDSs matrices ensure a slower release of TD in comparison with CTS/XG based formulations. Meanwhile, increasing DD resulted in a decrease of drug release. In addition, TD release from XGDS matrices was faster at pH (6.8) than at acidic pH (1.2). The matrix tablets based on CTS/XGDS4 (DD = 98.08%) were selected as the best candidates compared to the other systems in prolonging drug release. The optimal formulation was found to release 99.99% of TD after 24 h following a non-Fickian type.