Modulatory effect of polymer type and composition on drug release from sustained release matrix tablets of diclofenac sodium
The purpose of this study was to investigate the effects of polymer type and composition on drug release from the matrix of diclofenac sodium sustained release tablets formulated using three different granulation methods. Ten (10) batches of diclofenac sodium tablets (F01 - F10) were prepared by melt granulation, coacervation and physical blending using a combination of carnauba wax, Eudragit® and hydroxypropyl methylcellulose (HPMC) at various ratios. Their granules were evaluated for flow properties: flow rate, angle of repose, Hausner’s ratio and Carr’s index, before compression into tablets. Drug-excipient interactions were studied using DSC and FTIR. Post compression evaluation of the tablets such as weight uniformity, dimensions, friability, crushing strength and dissolution profile was also carried out. Granules prepared by melt granulation and coacervation methods were free flowing, while those from physical blending were fair in their flow properties. All the formulated tablets met BP official specifications with regard to weight, hardness and friability. With a constant amount of HPMC included in the tablets, Batches F01, F02, F04 and F05 showed decreased drug release with increase in the concentration of Carnauba wax or Eudragit® from 5 to 10 %, releasing over 90 % of their drug in 6 h. Batches without HPMC and containing 20 % of Carnauba wax or Eudragit® showed a lower release of 80%. Drug-excipient interaction studies showed no reaction between the drug and excipients used. Sustained release matrix tablets of diclofenac sodium were successfully formulated using HPMC as drug release modifier. Formulations F01 and F04 prepared with Carnauba wax and Eudragit® RL100 respectively, exhibited optimal drug release characteristics.
Keywords: diclofenac sodium, sustained release, release modifier, polymers, matrix tablets