Correlation of characteristics of gel extrusion module (GEM) tablet formulation and drug dissolution rate.

The purpose of the study was to characterize the swelling properties of controlled release tablet formulations with compositional and processing differences. A correlation was also established between the drug dissolution rate from the controlled release gel extrusion module (GEM) tablet and the swelling properties of the core tablet. The GEM tablet consisted of a core tablet of water swellable Carbopol polymer, a neutralizing agent, drug, and excipients. The tablet was subsequently coated with a rigid, water impermeable membrane. A number of holes were then drilled by laser through the impermeable membrane. Dynamic mechanical analysis (DMA), Perkin Elmer DMA7, was used to characterize the swelling properties. During the swelling measurements, the measuring probe and sample were completely submerged in the surrounding medium. The results showed that the formulation containing potassium phosphate dibasic as a neutralizing agent had the highest swelling rate. Correspondingly, this formulation had the highest drug dissolution rate over the same time period. The processing difference included wet granulation and dry roller compaction. The compositional differences included different neutralizing agents, binders or Carbopol polymers. The results showed a linear relationship (r(2)=0.954) between the swelling rates of the core tablets and the drug dissolution rates of GEM tablets. No correlation was found between the drug dissolution rates and either the maximum extent of tablet swelling or the time needed to reach the maximum extent of swelling. The results demonstrated that DMA could be used to support both formulation and process development to determine the effects of different compositions and manufacturing processes on drug dissolution rates for swelling controlled release devices.