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 compos
itions of these cellulose derivatives was investigated. Using mixture
design, the formulations with the best retardation properties were sel
ected. On the basis of these results, tablets with different compositi
ons containing 60% (300 mg) of theophylline were prepared. The simulat
ion was performed on a personal computer with the implemented digital
simulation language SIMCOS to predict steady-state plasma levels. It w
as established that formulation C, composed of 34.6% of MC, 4.7% of HP
MC, 0.7% of HPC and 60% of theophylline exhibits in vivo the same reta
rdation effect as commercially available theophylline tablets.