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 experim ental design based on the philosophy of Taguchi was applied to optimiz e the yield of the produced granules. Successively, the optimized pell ets were coated with an ethylcellulose pseudolatex preparation (Surele ase(R)) in a fluid bed coating machine using a bottom spray nozzle and a Wurster(R) column. Finally, these granules were compressed into tab lets of different hardnesses. The chosen statistical approach proved e fficient not only to find the optimal operating conditions for granula tion but it also appeared to define the characteristics of a process t hat was robust and nonsensitive to noise factors. Dissolution studies revealed a zero-order release of theophylline from the coated granules , but after the compression step, the ethylcellulose film was damaged and the drug release was immediate.