Development and Characterization of Linagliptin Microspheres Using 32 Full Factorial Design for the Management of Diabetes

Linagliptin is a dipeptidyl peptidase-4 inhibitor used to treat type 2 diabetes and is categorized as a BCS class III drug, having high solubility and low permeability, resulting in a very low bioavailability, 30%, of the drug. Microspheres have been formulated to increase the gastric retention time. The batches were formulated using a 32-full-factorial design of experiments, taking the concentration of ethyl cellulose, and speed of homogenizer as the factors, and % entrapment efficiency and particle size as the dependent parameters. The optimized batch, having 200 mg of ethyl cellulose and an 8000 rpm speed of homogenization, was formulated, which showed 80.3 % of the drug was released at the 8th hour. Mean particle size, % entrapment efficiency, and percentage yield of the optimized formulation were found to be 1.57 μm, 92%, and 96.99%. The kinetic model for the in vitro release of linagliptin microspheres was analysed, and results indicated that it followed the zero-order kinetic model based on the R² values.