Preparation and optimization of various parameters of enteric coated pellets using the Taguchi L9 orthogonal array design and their characterization

Duloxetine hydrochloride enteric coated pellets were formulated using fluidized bed. Three separate layers, the drug layer, the barrier layer, and the enteric layer, were coated onto the inert core pellets. The pellets were optimized with the acid resistance and drug release in simulated intestinal fluid as the process parameters, using the Taguchi L9 orthogonal array. Various other properties, such as surface morphology, bulk and tapped density, Hausner's ratio, hardness, friability, yield of pellets, moisture content, and particle size distribution, were also studied in the optimized pellets. The concentration of the enteric polymer played a vital role in acid resistance, while the type of enteric polymer affected the drug release in simulated intestinal fluid. In both cases, it was determined that binder polymer concentration was not affected much. The comparisons between the optimized pellets and a market formulation yielded f1 and f2 values within a range of 4–5 and 60–65, respectively. Three month stability studies, conducted at accelerated conditions, showed the optimized pellets to be stable. Taguchi plays an important role in optimizing parameters, and optimization of duloxetine hydrochloride can be achieved with minimal trials.