Effect of annealing time on the applicability of potato starch as an excipient for the fast disintegrating propranolol hydrochloride tablet

Starch is a cheap and easily available excipient in pharmaceutical manufacturing. Although tablet formulated containing native starch have rapid disintegrating property, these products cannot be commercialized due to their poor mechanical strength. Physical modification like annealing can greatly rectify this limitation of starches. However, the property of annealed starches generally varies with their preparation condition. The objective of this study was to evaluate the impact of processing time of starch annealing in its applicability as a direct compression polymer in the fast disintegrating propranolol hydrochloride tablets. Annealing starches with three different preparation times i.e., 8 h, 16 h, and 24 h were prepared from native potato starch. Thereafter, tablet formulations of propranolol hydrochloride were prepared using either native starch or one of the annealed starches by direct compression method. It was found that annealing successfully improved the mechanical strength of native starch without losing swelling character, making it suitable as a polymer for direct fast disintegrating tablets. However, the degree of crystalline perfection and mechanical strength was dependent on annealing time. Tablets made from 16 h annealing starch were found to be fastest disintegrating with immediate release of propranolol hydrochloride. Further increasing the annealing duration (24 h) resulted in enhancement of starch crystallinity with an elevation of tablet disintegration time. This study was therefore helpful in the development of immediate release direct compressible propranolol hydrochloride tablet using optimized annealing starch.