FORMULATION DESIGN AND IN VITRO EVALUATION OF BILAYER SUSTAINED RELEASE MATRIX TABLETS OF DOXOFYLLINE

Objective: To develop bilayer matrix tablet of Doxofylline by providing a loading dose followed by the maintenance dose that suppose to enhance the therapeutic efficacy the drug for acute and sustainable asthma. Methods: Both immediate release layer and sustained release layer were prepared by wet granulation methods. Different Pre compression and post compression characterization of the tablet were carried out. Swelling studies were carried out for all the formulation. To optimise the immediate release layer, similarity ( f 2 ) and difference factor ( f 1 ) were calculated and optimised IR formulation was used for all formulations of bilayer tablet. In-vitro release studies were carried out in USP II paddle type dissolution apparatus for different formulations and release kinetic studies were carried out different kinetic model. FTIR and DSC studies were carried out for pure drug Doxofylline, IR layer and SR layer of optimised formulation to know the physical and chemical compatibility of drug and excipients. Accelerated stability studies were carried out to confirm the stability of dosage forms. Results: Pre compression and post compression parameters satisfied with pharmacopeia specifications. The formulation that contained highest percent of HPMC had highest swelling index. Formulation DBMF 6 showed an initial release of 44% of drug within one hour as the loading dose and remaining drug were sustained release up to 12 h. Release kinetic followed Hixon-Crowell kinetic model with drug release mechanism quasi-fickian diffusion. From accelerated stability studies no significant changes in physicochemical properties were noticed. Conclusion: Doxofylline bilayer matrix tablets were successfully developed and can be used as an alternative to the conventional dosage form because it can be therapeutically beneficial for management of asthma.