Ultrasound Effect on Swelling Properties and Drug Release Behaviors of Spray-dried Tapioca Starch Tablets

Modified starches have been widely used as an excipient in matrix tablets to control drug release. A new processing method for the production of modified starch, high power ultrasonic treatment (400 W), was applied to native tapioca starch. The spray drying technique was used after modification (i.e., by ultrasonic or heat treatment). Matrix tablets were then prepared by direct compression using theophylline as a model drug. The effect of starch modification on swelling, erosion and in vitro drug release behaviors of compressed matrices was investigated in 0.1 N HCl or phosphate buffer (pH 6.8). The matrix tablets of modified tapioca starch formed a continuous gel layer while in contact with the aqueous medium undergoing a combination of swelling and erosion. The ultrasound-treated starch swelled and eroded less than the native starch and heat-treated starch, thus the drug release from matrix tablets using ultrasound-treated starch was slower. For these results, it can be concluded that the ultrasound-treated starch was a promising excipient for controlled drug release.