Formulation, release and stability study of Bupropion sustained release 150 mg using Hydroxypropylmethylcellulose (HPMC) 4000cps basis

In this study،formulation of sustained-releasingmatrix tablet of bupropion 150 mg، usinghydroxypropylmethylcellu lose (HPMC) 4000cps was evaluatedwith the aim of reducing the frequency of daily dose. The level of HPMC4000، polyvinylpyrolidone (PVP) and magnesium stearate (Mg St) was varied based on a 2level 3 factor factorial experimental designusing the release rate of the drug from the matrices as the response variable. Themechanism of drug release from hydrophilic matrix tablets is complicated but it is known to be related to dissolution of drug and its diffusion through the hydrated portion of matrix and erosion of the outer hydrated polymer on the matrix surface. Granules of the optimum formulations were compressed into tablets using EK-O lorsch single punch tablet machine. Evaluation of tablets including weight variation،crushing strength and friability demonstrated acceptable results. Based on dissolution data of the eight tablet formulations resulted from the experimental design، a polynomial regression equation was generated and used for obtaining the optimum formulations. Invitro dissolution tests also revealed sustained release of drug for an 8 hours period at the end of which almost complete release was achieved. According to release studies formulation A،AB and C has been selected for long term stability studies.