Modified Xanthan Gum as Hydrophilic Disintegrating Excipient for Rapidly Disintegrating Tablets of Roxithromycin

A hydrophilic excipient that could modulate the disintegration time was developed as disintegration aid for the tablets of the model drug roxithromycin. Xanthan gum (XG) was modified by sequential processes to obtain treated xanthan gum (TXG) and co-grinded with mannitol to produce co-grounded treated xanthan gum (C-TXG) and was characterized by Scanning Electron Microscopy (SEM), Diffuse Reflectance Spectroscopy (DRS) and X-Ray Diffraction (XRD). SEM revealed structural changes attributable to processing steps without chemical modification that was established by DRS. The XRD analysis of C-TXG exhibited a crystallinity index of 87% and optimum micromeritic properties suggesting it to be amenable to direct compression. Consequently, directly compressible tablets of roxithromycin were formulated (F1–F6) using modified xanthan gum and other directly compressible hydrophilic excipients. The tablets formulated with lower level of C-TXG and higher level of microcrystalline cellulose (F4), exhibited least in vitro disintegration time without friability concerns. A nine fold reduction in the lag time of the optimized formulation when compared to the experimental conventional formulation was observed. The twelve months aged samples demonstrated no change in the in vitro drug release profile, disintegration time and were found to be stable.