Mixture design of theophylline retard formulation

Three different cellulose derivatives (hydroxypropyl cellulose (HPC), hydroxypropyl methyl cellulose (HPMC) and microcrystalline cellulose (MC)) were used to prepare tablets containing 10% of theophylline with the aid of wet granulation. The retardation effect of different compositions of these cellulose derivatives was investigated. Using mixture design, the formulations with the best retardation properties were selected. On the basis of these results, tablets with different compositions containing 60% (300 mg) of theophylline were prepared. The simulation was performed on a personal computer with the implemented digital simulation language SIMCOS to predict steady-state plasma levels. It was established that formulation C, composed of 34.6% of MC 4.7% of HPMC 0.7% of HPC and 60% of theophylline exhibits in vivo the same retardation effect as commercially available theophylline tablets.