Microencapsulation of Ibuprofen by A Coacervation Process Using Eudragit L100–55 as An Enteric Polymer

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Abstract
Ibuprofen microcapsules were prepared using Eudragit as enteric coating material and a simple coacervation method as coating process. Preliminary experiments based on results published with cellulose acetate phthalate led to the formation of a precipitate rather than a coacervate. Adjusting the polarity of the solvent in the Eudragit system by the addition of cosolvents enabled the transformation of the precipitate into a coacervate. This behaviour was qualitatively explained using the solubility parameter approach. The coacervate phase obtained from a system containing 2-propanol as cosolvent was assayed quantitatively in the absence and in the presence of ibuprofen. Due to the increased solubility of the drug in the cosolvent containing system, the composition of the coacervate phase was significantly altered when compared to a system without drug. The surface morphology of the microcapsules was assessed by scanning electron microscopy. The enteric properties of the microcapsules were tested according to the USP XXII test procedures. The permeability of the wall was evaluated by a dissolution test performed at pH 4. During stability testing over a period of 6 months the quality of the ibuprofen microcapsules remained almost unchanged.