Formulation and Evaluation of Carbamazepine 200 mg Controlled Release Tablets Using Different HPMC Grades

Possible interaction between carbamazepine and different HPMC grades was done using DSC thermal analysis. The results indicated that the drug was compatible with these grades. Seven preparations of carbamazepine 200 mg controlled release tablets were prepared by wet granulation method and one preparation was prepared by direct compression method where different HPMC grades with different ratios were used. Concerning uniformity of weight, hardness and assay; all tablets conformed to pharmacopeal limits. Dissolution of the prepared tablets was done using basket method for 24 hours and paddle method for 4 hours. Tablets prepared by 30.0, 35.0 and 40.0% w/w HPMC K 100, 25.0% HPMC K 100 in combination with 5.0% HPMC K 4M and 15.0% w/w HPMC K 4M were conforming to USP limits, while tablets prepared by 15% K4M are not conforming to these limits. Tablets prepared by 12.5% HPMC K 15M by direct compression technique showed similar dissolution values to the innovator in five different media: distilled water, distilled water containing 1.0% SLS, buffer pH 1.2, acetate buffer pH 4.5 and phosphate buffer pH 6.8. The difference and similarity factors were found very acceptable. Scaling up of carbamazepine 200 mg controlled release tablets formulation from lab scale (500 tablets) to full production scale (500,000 tablets) was done. All the results of the scaling up were conforming to specifications and indicated that scaling up process has been done successfully and drug release kinetics indicated that the drug dissolution was zero order.