FORMULATION AND EVALUATION OF BILAYER TABLETS BY MELT GRANULATION TECHNIQUES

The development of bilayer tablets has emerged as a promising strategy for the delivery of drugs requiring immediate and sustained release within a single dosage form. This study focuses on the formulation and evaluation of bilayer tablets using the melt granulation technique, an advanced method that eliminates the need for solvents and improves process efficiency by utilizing thermoplastic binders. The bilayer system was designed to consist of two separate layers: an immediate release layer to provide rapid onset of action and a sustained release layer to maintain therapeutic drug levels over an extended period. Various pharmaceutical excipients were screened and selected based on their compatibility and processing characteristics. The melt granulation process involved heating hydrophobic binders above their melting points and blending with active pharmaceutical ingredients (APIs) and other excipients to form granules without water or organic solvents. The prepared granules were compressed into bilayer tablets using a single rotary tablet press. Comprehensive evaluation was carried out to assess both pre-compression and post-compression parameters. Flow properties such as angle of repose, Carr’s index, and Hausner’s ratio were analyzed to ensure proper compressibility of granules. Post-compression evaluation included hardness, friability, weight variation, thickness, disintegration time, drug content uniformity, and in-vitro drug release studies. The drug release profiles of both layers were investigated using dissolution testing in simulated gastrointestinal fluids, demonstrating a biphasic release pattern an initial burst followed by a controlled release over 12 hours. Stability studies conducted under ICH guidelines revealed no significant changes in physical appearance, drug content, or release profiles over a 3-month period. The results indicate that the melt granulation technique is a robust and solvent-free approach suitable for bilayer tablet formulation, offering advantages such as enhanced stability, simplified manufacturing, and improved patient compliance. This study supports the potential of bilayer systems produced via melt granulation in developing combination therapies for chronic conditions. KEYWORDS: Bilayer tablets, melt granulation, immediate release, sustained release, oral drug delivery, solvent-free technique, thermoplastic binders, drug release kinetics, tablet compression, pharmaceutical formulation, stability studies, controlled drug delivery, solid dosage forms, patient compliance, pre-compression and post-compression evaluation.[1][2][3]