Formulation and evaluation of sustained release dosage form of theophylline using a combined hydrophobic and hydrophilic matrix

Combination of aliphatic alcohol (cetyl alcohol) and partially hydrated methylcellulose was investigated as a sustained release matrix. Theophylline is used as a model drug for evaluating the matrix system. Cetyl alcohol and methyl cellulose were used in different proportions i.e., 2:1, 3:1, and 4:1 along with usual tablet additives, lactose and talc. The matrix component was varied from 20, 25 and 30% w/w of total tablet weight. The in vitro release data showed that 30% w/w total matrix component gave extended release of theophylline for more than 8 h. Analysis of drug release rate from the matrix system indicated that the drug was released by anomalous diffusion obeying first order rate kinetics.