Evaluation of Ethylcellulose-Coated pellets Optimized using the Approach of Taguchi

Spherical granules of theophylline with microcrystalline cellulose and lactose were prepared in a high-speed granulator. An original experimental design based on the philosophy of Taguchi was applied to optimize the yield of the produced granules. Successively, the optimized pellets were coated with an ethylcellulose pseudolatex preparation (Surelease®) in a fluid bed coating machine using a bottom spray noule and a Wurster® column. Finally, these granules were c ompressed into tablets of different hardnesses. The chosen statistical approach proved efficient not only to find the optimal operating conditions for granulation but it also appeared to define the characteristics of a process that was robust and no sensitive to noise factors. Dissolution studies revealed a zero-order release of theophylline from the coated granules, but after the compression step, the ethyl cellulose film was damaged and the drug release was immediate.