Evaluation of the Binding Property of Some Binders in Metronidazole Tablet Formulation

The binding property of five (5) commonly used binders in metronidazole granule and tablet formulations was studied. The binders studied included gelatin, polyvinylpyrrolidone (PVP), carboxymethylcellulose (CMC), maize starch and guar gum. The binders were incorporated as 5%w/w of tablet weight in each case. The granules were formulated by the wet granulation technique while the tablets were prepared by compression. The properties of granules evaluated included flow rate, angle of repose, bulk and tapped densities, Hausner’s ratio, Carr’s index and moisture content. Tablet properties studied included weight uniformity, hardness, friability, thickness and diameter, disintegration time and dissolution rate. Results indicated that granules containing guar gum or PVP possessed flow properties superior to those of other binders, while those containing gelatin possessed the least flow property. In terms of packing characteristics, granules containing CMC were better than others. The mechanical strength of tablets containing gelatin, PVP or CMC was superior to those made with either guar gum or maize starch. In terms of release of metronidazole, tablets containing PVP, gelatin or guar gum were more efficient in releasing the drug, while those made with CMC was the least. On the basis of these, good metronidazole tablets could be formulated using PVP, gelatin or guar gum. On the other hand, maize starch or CMC may not be recommended as a binder for metronidazole tablets because of high friability or poor release respectively.