FORMULATION AND EVALUATION OF CARBAMAZEPINE BILAYER TABLET FOR BIMODAL RELEASE

Carbamazepine (CBZ) has long been a therapeutic option for bipolar disorder. Carbamazepine is used to treat acute manic and mixed episodes associated with bipolar I disorder.  In the present study, bilayer tablet was developed to improve dosing convenience and decrease daily fluctuations in serum CBZ concentration, thereby lowering the incidence of adverse events. In bilayer tablet one layer provides the loading dose by immediate drug release and another layer provides the maintenance dose up to 12 hrs by sustained release. The drug excipient compatibility study was carried out by FTIR and DSC techniques; there was no interaction found. Cross povidone was used as a superdisintegrant in the immediate release layer and controlled release fraction was formulated by using HPMC K 100 polymer. The prepared granules were evaluated for angle of repose, bulk density, tapped density, and compressibility index which showed satisfactory results. The prepared bilayer tablets were evaluated for thickness, hardness, friability and in-vitro release studies. In-vitro dissolution study was carried out for 12 hours using USP dissolution apparatus I using 1.2 pH and 7.4 phosphate buffer as dissolution medium. The bilayer tablet showed initial burst release to provide the loading dose of drug followed by sustained release up to 12 hours. Concentration of polymer and superdisintegrant ratio influenced drug release profile. As the polymer concentration was increased in sustained release layer the % drug release decreased.