Taste masking and molecular properties of metformin hydrochloride-indion 234 complexes.

Metformin hydrochloride is an oral antidiabetic biguinide agent, used in the management of non-insulin-dependent (type-2) diabetes mellitus. The purpose of present work was to formulate tasteless complexes of metformin hydrochloride with indion 234 and to evaluate molecular properties of drug complexes. The drug loading onto ion-exchange resin was optimized for mixing time, activation, effect of pH, mode of mixing, ratio of drug to resin, and temperature. Drug resin complexes (DRC) were evaluated for taste masking and characterized by x-ray diffraction study and infrared spectroscopy. Metformin hydrochloride release from DRC is obtained at salivary and gastric pH and in the presence of electrolytes. The efficient drug loading was evident in batch process using activated indion 234 with a pH of 3.5 and drug-resin ratio of 1:1.2, while temperature enhances the complexation process. Infrared spectroscopy revealed complexation of –NH (drug) with indion 234. DRC are amorphous in nature. Drug release from DRC in salivary pH was insufficient to impart bitter taste. Volunteers rated the complex as tasteless and agreeable. Complete drug release was observed at gastric pH in 3 h. The drug release was accelerated in the presence of electrolytes. Indion 234 is inexpensive, and the simple technique is effective for bitterness masking of metformin. Key words: Characterization, electrolyte release, metformin hydrochloride, Indion 234, tasteless complex.