Ibuprofen Encapsulation by Eudragit RS100 as Microspheres: Preparation and Drug Release

The success in the preparation of Eudragit RS100 microspheres in 0.IN HCI solution using gelatin as antiaggregating agent, encouraged the selection of an acidic drug to be encapsulated using a solvent evaporation technique [1]. Ibuprofen is a non-steroidal, anti-inflammatory, analgesic and antipyretic drug approved for use as adjunct therapy in the treatment of rheumatoid and osteoarthritis [2]. Chemically, it is a propionic acid derivative [3]. It is slightly soluble in water and has a poor wettability. However, it is completely bioavailable and is rapidly absorbed after oral administration. It gives maximum plasma concentration within 2 hours [4]. The major side effect of Ibuprofen therapy involves gastrointestinal toxicity. Kawashima et al. [5] prepared controlled release Ibuprofen microspheres using acrylic polymers. An ethanolic solution of Ibuprofen and an acrylic resin was poured into an aqueous medium with stirring. The finely dispersed ethanolic droplet-like coacervates formed in the aqueous phase were gradually solidified and transformed into microspheres during agitation. Kawashima stated that the concentration of drug and polymer and the agitation speed of the system controlled the size of the microspheres. Also, Ibuprofen prolonged-release spherical micrometrics were prepared by using Eudragit RSI00 and a novel emulsion-solvent diffusion method [6]. Examining cross sections of the formed spherical matrix before and after dissolution studying using a scanning electron microscope and a porosimeter indicated that the resultant micro matrix had a sponge-like internal structure. The spherical matrix was successfully recovered with a relatively high concentration of drug in ethanol (0.4-0.6gm/ml) and over a wide temperature range (5-35°C). The size of the spherical matrix could be easily controlled by varying the agitation speed of the system and by adjusting the concentration of the emulsifier added to the aqueous medium. Also in relation to the solvent diffusion procedure it was reported that Eudragit RS100 and RL100 microspheres containing Ibuprofen were prepared and evaluated. The microspheres were prepared by modified quasi-emulsion solvent diffusion method. The author reported when there was an initial difference of temperature between the aqueous phase and dispersed emulsion phases, the yield of preparation was increased distinctly. The drug loading capacities were very high for all formulations of the microspheres obtained. Mean particle size changed by changing the drug-polymer ratio, volumes of solvent or polyvinyl alcohol concentration. The flow properties were much improved over those of the original crystals [7].