Exploring the significant role of natural polymers in developing drug delivery systems has been a promising area of research interest. The current investigation uses a D-optimal quadratic mixture design to design and evaluate neem and tamarind gum-based vildagliptin extended-release matrix tablets. Studying the combination effect of gums is one of the major objectives. Initial screening studies were performed to select the factors and their levels. The variables selected at different levels in mg/tablet are neem gum, tamarind gum, polyvinylpyrrolidone, and lactose monohydrate. Based on the screening experiments with both gums, the polymer content of 165 mg was chosen as the highest level in the DOE. Nineteen runs were generated to screen the desired parameters as responses. The total weight of the formulation was kept constant at 275 mg. Time (hours) required for 50 %, 90 % and 100 % of drug release and tablet hardness were selected as the responses for each run. The wet granulation method was adopted, and the critical variables were optimised using the design of experiments following Design Expert software. Statistical analysis was conducted, and the optimised formulations were prepared and evaluated to compare with the predicted responses. Stability studies were performed for the optimised batches. Results indicated that the prepared batches met the compendial limits and confirmed the application of neem and tamarind gum in the development of extended-release tablets of vildagliptin for 24 h. An optimised formulation comprising of 16.52 mg of neem gum and 148.48 mg of tamarind gum with a hardness of 7.5-8.5 kp produced 50 %, 90 % and 100 % drug release in 12, 22 and 25 h.
Keywords: D-optimal; Natural gums; Neem gum; Plant polysaccharides; Tamarind gum; Vildagliptin.
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