Enhancement of solubility and effect of granulation methods on drug release in sustained release matrix tablets of a poorly soluble drug

Domperidone, a BCS Class II drug chosen as a model drug which is highly permeable and poorly soluble, mainly used in the treatment of Emesis. It has a strong affinity for D2 receptors, chemically related to Haloperidol, but pharmacologically related to metaclopramide. Sustained release tablet of Domperidone are preferred because of prolonged drug release in order to reduce the frequency of dosing. In the present study, it was decided to design controlled release formulation of Domperidone with pH dependent release profile so as to minimize/prevent initial drug release in the stomach in order to reduce the possible gastro-irritant and ulcerogenic effects of the drug The study was carried out using release retarding polymers like HPMC (hydrophilic matrix polymer), Eudragit (polyacrylate polymers) and natural polymers like guar gum and xanthan gum were used. An ideal matrix formulation prepared using different polymer and diluent concentrations. The formulation were prepared using various compression techniques like wet granulation technique and direct compression techniques in order to release their contents in a sustained manner over a certain period of time. As Domperidone is class II drug having low solubility and more permeability and, the solubility of Domperidone was initially enhanced by preparing solid dispersions using solvent evaporation method by using drug and polymer (β-cyclodextrin) in three different ratios i.e. 1: 0.75, 1: 1, 1: 1.5 and the solid dispersion mixture containing drug and polymer in the ratio 1: 1.5 showed 97% drug release in one hour was optimized as the best mixture. In the present work drug and polymer mixture in the ratio 1: 1.5 was further formulated into tablets by incorporating natural and synthetic gums by using different granulating techniques like direct compression and wet granulation in three different concentrations. Formulation (F3) containing drug and Xanthan gum in the ratio 1: 1 prepared by wet granulation technique could sustain the drug release over a period of 12h and hence considering all the post compression parameters it was optimised as the better formulation. FTIR, DSC, X-Ray Diffraction, SEM studies were performed for optimised solid dispersion mixture and also the optimised formulation.