FORMULATION AND EVALUATION OF MICROCRYSTALLINE TAPIOCA STARCH AS A FILLER-BINDER FOR DIRECT COMPRESSION

Tapioca starch (NTS) was modified physically at molecular level by annealing and subsequently subjected to enzyme hydrolysis to obtain a more functional filler-binder “microcrystalline tapioca starch (MCTS)”. NTS was extracted from cassava tuber (Mannihot esculenta cranzt) using a standard method. The powder suspensions were prepared in concentration of 40 %w/w in five separate conical flasks. The starch granules were annealed for 1 h and subsequently hydrolyzed with α-amylase at 58^o and pH 7 for 1, 2, 3, 4, and 5 h in a water bath. The reaction was terminated and neutralized with 0.1 N HCL and 0.1 N NaOH respectively. The MCTS was washed, recovered by sedimentation and air dried at room temperature for 72 h. Following characterization, the granules that were modified for 3 h, sieved fraction >75-250 µm was selected and compacted at a range of compression load 2.5 to 12.5 KN. The average granule size of NTS, annealed tapioca starch (ATS), and MCTS were 10 µm, 11.5 µm, and 13 µm respectively. Average flow rate, angle of repose and compressibility index were 2 g/s, 43^o, 50% for NTS respectively, and 2.5 g/s, 35^o, 37.5 % for MCTS. The crushing strength for NTS, ATS and MCTS are: 30 N, 90 N and 100 N after 3 h of annealing and hydrolysis respectively, compressed at 6 metric units. MCTS was compared with Starlac®, Cellactose® and MCC. The onset of plastic deformation P_y (yield value) were: Cellactose (24.2 MNm^-2)>MCC (25 MNm^-2)> MCTS (143 MNm^-2) =Starlac (143 MNm^-2). The degree of plastic deformation occurring during compression (P_k) is in the following order:  Starlac^® (17 MNm^-2)>MCTS (17.7 MNm^-2)>MCC (18.6 MNm^-2)>Cellactose^® (19.1 MNm^-2). MCTS is more superior in functionality than Cellactose and MCC. The dilution potential obtained for MCTS, compacted with paracetamol (PCM) and ascorbic acid (AA) as active drug (API) were: 20 %w/w PCM and 40 %w/w AA with MCTS. The hardness of MCTS containing 40 % AA was found to be 58 N;   MCTS can be used to formulate tablets of both poorly compressible and moisture sensitive API.