Starch is a readily available excipient which finds application in the pharmaceutical industry as binders, diluents and disintegrants. The use of starch is however limited by its poor flow characteristics. Co-processing exploits the desirable attributes of excipients, while masking the undesirable properties. Co-processed starch, thus presents great potential for use in formulation of directly compressed tablets which require materials with strong inherent cohesive and free flowing properties. In this study, Dioscorea dumentorum (Family: Dioscoreaceae) Starch (DdS) is co-processed with silicified rice starch (SRS) obtained from Oryza sativa; Family: Poaceae was incorporated as a disintegrant in directly compressed paracetamol tablet formulations in comparison with silicified rice starch and Avicel® as the official standard.
Rice and DdS were extracted following standard procedures. The rice starch was silicified using colloidal silicon dioxide and co-processed with DdS in the ratio SRS:DdS (1:2). The DdS, SRS and SRS:DdS (1:2) were characterized using FTIR, particle size, angle of repose, bulk and tapped densities, Hausner ratio and Carr’s index. Paracetamol powder was directly compressed into tablets incorporating the co-processed excipient (SRS:DdS; 1:2) as disintegrants alongside Avicel®, SRS and DdS at varying concentrations (10% w/w, 15% w/w, 20% w/w, 25% w/w). The properties of the tablets were evaluated using friability, crushing strength and disintegration as the assessment parameters. Measurements were made in triplicates and the results were statistically analyzed.
The yield of the starches was 41% w/w and 39% w/w for rice starch and DdS respectively. Silicifying the rice starch markedly improved the flow of the starch with a change of Carr’s index and Hausner ratio from 16.7 and 1.32 to 2.33 and 1.02 respectively. Tablets containing Avicel® had better crushing strength and friability values than those containing SRS: 2DdS at all disintegrant concentrations. The disintegration times for Avicel® and SRS: DdS compared favourably at all concentrations of disintegrant and at 15% w/w disintegrant, SRS: DdS showed better disintegrant properties than Avicel®.