TABLETING BEHAVIOUR OF SOME DEPOLYMERIZED LOCAL STARCHES

TABLETING BEHAVIOUR OF SOME DEPOLYMERIZED LOCAL STARCHES

Abstract:

Starches extracted from millet, sorghum and yam were subjected to various degrees of hydrolysis. Investigations showed that the starch particles remained superficially unchanged but microscopic examination revealed a tendency of the particles to be more regularly shaped and there was a gradual reduction of average particle size with increasing depolymerization. It was also shown that hydrolysis generally improved the flow of all starch specimens, except for modified millet starch (MMS) which exhibited an initial increase in flow followed by a reduction with increase degree of depolymerization. In an evaluation of the compressibility of the starches in relation to degree of hydrolysis, it was observed that acid modification improved compressibility of all starch samples, and that with increased hydrolysis, there was improved compressibility. Compressibility as determined by tablets’ hardness and density shows MMS to be the most compressible followed by modified sorghum starch (MSS) and modified yam starch (MYS) respectively. Microcrystalline cellulose (MCC) compressed better than all the modified starches but tablets made from products of the highest degree of starch hydrolysis had very good physical properties comparable to those made from MCC. All the parent starches were unable to form coherent tablets even at very high compression pressure settings. Using the modified starches as direct compression filler-binder-disintegrant in a Trimethoprim tablet formula, tablets with greater hardness and density values were obtained and were less friable compared to tablets of the modified starches alone. A study of the compactional behaviour of physical mixtures of the modified starches with MCC and with Starch 1500 respectively indicated better flowability for all the modified starches irrespective of starch type or mixture composition compared to the modified starches alone. The binary mixtures with MCC flowed better than those with Starch 1500. Increasing the proportion of modified starch in the mixtures resulted in reduced flow. MYS mixtures compacted best at all proportions of mixing. In a comparative study of the properties of tablets from the unmodified starches and their hydrolysed forms as fillers respectively in wet granulation tableting, it was found that flow of the granules made from starch in their unmodified forms was lower than those from the modified starches. Compared to the direct compression tableting, very low compression forces were required to compact the granules to produce tablets with good physical properties. In addition, tablets made from modified starches as fillers possessed better tablet properties than those from their parent forms.

TABLETING BEHAVIOUR OF SOME DEPOLYMERIZED LOCAL STARCHES

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