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Aim: Studied the critical factors in the design of an osmotic pump with metformin release rate constant at 4%/hr in diabetes mellitus within 24 hr. with the goal to reduce daily medications. Study Design: Experimental design 32 Methodology: In vitro drug release profiles for 24h. The effects of different formulation variables, that is, concentration of hydrophilic polymer, diameter of drug releasing orifice and coating thickness, on the drug release profile were investigated. Also, the impact of pH, osmotic pressure and morphology with stereo microscopy and scanning electronic microscopy of the osmotic pumps were investigated. At last, osmotic pumps surface was analyze with scanning electronic microscopy. Results: Metformin osmotic pump were successfully prepared in this study to overcome the weak point of multiple doses and great concentration fluctuation of metformin. The formulation determined finally have a release orifice of 700 mm and 3.0% of weight gain, achieved the desired effect which can realize the constant drug release rate at the first 24 hr. Conclusion: The developed osmotic systems have a linear release near 4%/hr. and demonstrated that the behavior was independent of the agitation intensity and the pH of the gastrointestinal apparatus. |
