Development of ethylcellulose-polyethylene glycol and ethylcellulose-polyvinyl pyrrolidone blend oral microspheres of ibuprofen

Ibuprofen (IBP) was successfully encapsulated in ethylcellulose (EC) microspheres by oil-in-water solvent evaporation method. Dichloromethane (DCM) was used as the dispersed phase and distilled water was used as a dispersing medium. The objective of this work was to develop and observe the effect of formulation parameters on the physical characteristics of the resulting microspheres. The percent recovery of microspheres, their hydration rate, IBP loading efficiency and the drug release rate from microspheres were analyzed. Almost spherical microspheres having an encapsulation efficiency of 90-99 % were obtained. The drug release was also controlled to a great extent by the addition of water soluble polymers polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP). Decreasing the concentration of EC in the dispersed phase decreased the recovered weight. But this decrease in polymer concentration and increase of pore formers like PEG and PVP increased the release rate of the drug from microspheres, their hydration, drug loading as well as encapsulation efficiency. FTIR and XRD confirmed the absence of drug polymer interaction and amorphous state of drug after encapsulation. Moreover, the release pattern did not show any burst effect indicating that the absence of free ibuprofen on the surface of formed microspheres and formulations containing PVP provide better control release than PEG containing formulation. Drug release mechanism at pH 6.8 in all formulations is anomalous except the formulation containing 400 mg of PEG as channeling agent, which shows super case II transport.