DEVELOPMENT AND CHARACTERIZATION OF BILAYER TABLET CONTAINING TRAMADOL AND PREGABALIN AS A GASTRIC BUOYANT DRUG DELIVERY SYSTEM FOR COMBINATION PHARMACOTHERAPY OF NEUROPATHIC PAIN

Experiments were performed to design, develop and characterize bilayer buoyant tablets with Tramadol (TH), immediate release layer and Pregabalin (PGB), sustained release layer. Super disintegrants like crosscarmellose sodium and sodium starch glycolate, for IR layer where as Hydroxypropyl methylcellulose (HPMC-K4M, HPMC-K100M) and sodium carboxymethyl cellulose, as sustaining polymers for SR layer and sodium bicarbonate which liberates carbon dioxide for adequate buoyancy, was used in the bilayer tablet. FT-IR and DSC studies were conducted to evaluate drug and excipients compatibility. A full two level factorial experimental design was used for sustaining PGB release from buoyant SR layer. More than 90% of Tramadol was released from IR layer within 30 min. Diffusion exponents (0.36-0.55) and (T₅₀%) time required for dissolving 50% of drug (1.96-3.31h) was determined for all SR tablet formulations. Optimised (S4) formulation exhibited 95.28% PGB released over 12 h. Since neuropathic pain is very difficult to treat, a delivery system for combination pharmacotherapy containing immediate releases of TH a unique powerful painkiller to provide instant pain relief and sustained release of PGB, the choice of drug in first-line treatment for various neuropathic pain syndromes can provide excellent therapeutic result by suppressing burning-fire pain stimulation of nerves with once a day administration.