Effect of Polymer Blend on Diltiazem HCl Matrix Tablets Prepared by Direct Compression

The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on Deltiazem (DZ) directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (DZ1) exhibited the highest hardness values compared to the other formulae which based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for DZ formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of DZ from formulae DZ 2 and DZ 4 that based on the composition (2KL SR: 1EC) and (1KL SR: 2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR(DZ), the release rate was greatly retarded.