Hot melt granulation: a facile approach for monolithic osmotic release tablets

The aim of this work was to develop and evaluate an extended release matrix tablet of glipizide (GP), an oral hypoglycemic agent. Matrices of GP were prepared using microcrystalline cellulose Avicel(?) PH 112, sodium chloride (SC) and polyethylene glycol 6000 (PEG). The content of Kollidon SR (KR), hydroxypropyl methylcellulose K4M premium CR grade (HM) and polyethylene oxide WSR 303 (PO) and/or magnesium hydroxide (MH) was varied in different formulations. All the formulations were processed by hot melt granulation technique. GP release was observed to be influenced by the amount of SC and MH present in the core formulation. The matrix tablets were coated with a solution containing combination of cellulose acetate 398.10 (CA) and PEG. The release of GP was observed to be inversely proportional to the weight of the coating membrane. Matrices containing PO in combination with SC and MH (14.28:8.56) showed significantly higher degree of hydration and swelling that was evident in the surface texture as visualized by scanning electron microscopy (SEM). Results of SEM studies confirmed the presence of pores in the semi-permeable coating membrane from where the GP release would have occurred. The release of GP from this formulation was similar to that of the marketed extended release tablet as judged from similarity factor (f2) analysis, which yielded a value of 74.7. The optimized formulation was found to be stable when tested according to long term and accelerated storage conditions of ICH guidelines upto 3 months.