Hydrophilic matrices, especially HPMC based, are widely used to provide sustained delivery where drug release occurs mainly by diffusion. A 32 full factorial design was used to develop and evaluate HPMC matrix tablet for sustained delivery of diclofenac. The influences of polymer concentration/viscosity, diluent type/ratio, drug load/solubility, compression force and pH change on drug release were investigated. Ten tablet formulations were prepared using wet granulation. HPMC K15M (10-30% w/w) was used as the polymer forming matrix. The release kinetics, compatibility studies, lot reproducibility and effect on storage were discussed.
Increasing polymer concentration and compression force showed antagonistic effect on release rate. Mannitol tends to increase release rate more than lactose. Reversing diluent ratio between lactose and MCC did not affect
drug release. Changing pH resulted in burst release whereas drug solubility is pH independent. F1 showed similar release to VoltarenÆ SR and followed Higuchi model. Drug and polymer were compatible to each other. The
formulation is stable at long and intermediate conditions with a significant increase in release rate at accelerated conditions due to water uptake and polymer swelling. The developed formulation was successful for a sustained delivery of diclofenac.