BILAYER TABLET OF TRAMADOL AND GABAPENTIN FOR COMBINATION PHARMACOTHERAPY OF NEUROPATHIC PAIN: DEVELOPMENT AND CHARACTERIZATION

Abstract

Objective: Experiments were performed to design, develop and characterize bilayer buoyant tablets having tramadol (TH), immediate release (IR) layer and gabapentin (GBP), sustained release (SR) layer.Methods: Natural hydrophilic polysaccharide disintegrants were modified by sequential processes to obtain treated xanthan gum (TXG) and treated gellan gum (TGG), utilized for IR layer whereas carbopol and sodium carboxymethylcellulose, as sustaining polymers for SR layer and gas producing substance sodium bicarbonate which librates carbon dioxide for adequate buoyancy, was used in formulated bilayer tablet. A full two-level factorial experimental design was used for sustaining GBP release from buoyant SR layer.Results: Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) studies conducted, explain overall drug and excipients compatibility. More than 90% of tramadol was released from IR layer within 30 min. Diffusion exponents (0.36-0.59) and T50% (2.4-4.4h) were determined for all SR tablet formulations. Optimised (S7) formulation exhibited 95.77% GBP released over 12h.Conclusion: Developed tablet can provide excellent therapeutic result by the sequential immediate release of TH and sustained release of GBP for effective combination pharmacotherapy of neuropathic pain with once a day administration.