Controlled release matrix tablets for diclofenac sodium were developed in this study. Five matrix-tablet formulations were prepared by granulating two viscosity grades of HPMC (hydroxylpropylmethylcellulose) in varying ratios with water in the planetary mixer. The in-vitro dissolution tests indicate that all five matrix formulations prolong the release of diclofenac sodium. The main factors controlling drug release were the HPMC viscosity grade and the amount of HPMC used. The larger the amount of high viscosity grade HPMC used, the slower the resultant release rate of diclofenac sodium. There was no significant degradation of diclofenac sodium or change in drug release rate in any of the five formulations during a three-month period of stability testing. The sustained release ability of four formulations was further demonstrated in an in-vivo study in six healthy subjects. There were in-vitro/in-vivo correlations between C-max, AUC(0-14), and the time for 50 or 80% drug to be released.
