FORMULATION AND EVALUATION OF ENTERIC COATED CONTROLLED POROSITY OSMOTIC MATRIX TABLETS OF MODEL DRUG

It is a novel osmotically driven matrix system, which utilizes the property of hydrophilic polymers to swell and gel in aqueous medium forming a semi-permeable in situ. Release from such a matrix system containing an osmogent could, therefore, be modulated by the osmotic phenomenon. OMT thus judiciously combines both matrix and osmotic characteristics resulting in a quantum improvement in drug delivery from swellable matrix systems. Diclofenac Sodium was prepared in the form of tablets and evaluating the various processing parameters including pre-compression and post-compression parameter with in vitro drug release studies in 0.1 N HCl (pH 1.2) and Phosphate buffer(pH 6.8). Ten formulations containing varying proportions of polymer Guar gum and release modifying agent used as NaCl,PEG-400.and fixed amount of PVPK30,SLS, Magnesium stearate & Lactose were used as binder, wetting agent, lubricant & glidant respectively. The tablets were prepared by Wet granulation Method, The different levels of enteric-coating membrane could prevent Eudragit L100-55 (containing PEG-400) from forming pore or rupture before contact with simulated colonic fluid, but had no effect on the drug release. Drug release rate from 1h-12h were taken as responses. The increase in concentration of osmotic agent with decrease in concentration of polymer after a limit, changes the release from zero order to Higuchi based release. The optimized formulation F8 follows osmosis release mechanism. The DSC and SEM studies revealed that no physicochemical interaction between excipients and drug and good pore form. Stability studies revealed that optimized formulation was stable.