Preparation and Physicochemical Characterization of Acid Modified Cassava Starch and Its Evaluation as Directly Compressible Tablet Excipient

Abstract

Cassava starch was partially hydrolyzed in 6% HCl solution at room temperature for 192 h, dried using oven- and spray-drying techniques and subsequently evaluated as a direct compression excipient in pharmaceutical tablet formulations. Acid modification enhanced the  crystallinity while the amylose content decreased from 15.24% to 5.14%. Native cassava starch (NCS) and oven -dried acid modified cassava starch (AMCS) exhibited poor flow characteristics, whereas spray dried AMCS was found to be free flowing powder with 25.12 ± 2.88° angle of repose and 13.63 ± 0.52 g/sec flow rate. Lubricant sensitivity and dilution potential of spray dried NCS and spray dried AMCS were investigated by incorporating magnesium stearate and paracetamol, respectively, in tablet formulations. Spray dried AMCS and Starch 1500^® tablets were produced with acceptable tablet characteristics (a minimum of 50 N crushing strength and < 1% friability) up to 0.75% and at 0.25% magnesium stearate concentrations, respectively. The spray dried AMCS was able to accommodate up to 40% paracetamol by weight with crushing strength of 55.90 ± 2.84 N and friability of 0.80 ± 0.06%. Starch 1500^® tablets were more friable and exhibited lower crushing strengths at all paracetamol concentrations as compared to the spray dried AMCS tablets (P < 0.05). The dilution potential and lubricant sensitivity of the spray-dried AMCS were significantly higher than those of spray dried NCS and Starch 1500^®. Hence, spray dried AMCS has the potential for application as a directly compressible tablet excipient.

Keywords: cassava starch, acid modification, spray drying, direct compression, tablet excipient