Ibuprofen-loaded microspheres based on a co-polymer of Eudragit^® RS 100 and RL 100: Formulation, swelling and drug release properties

Abstract

The objective of this study was to encapsulate ibuprofen in microspheres based on a co-polymer of Eudragit^® RS100 and RL100 with a view to achieving a controlled release of the incorporated drug. The microparticles were prepared by an o/o emulsion-solvent evaporation method using varying polymer ratios and polymer concentrations as independent variables. The prepared microspheres were characterized with respect to particle size, morphology, swelling properties and bioadhesiveness. The in vitro release profile of ibuprofen from the formulation was evaluated in 0.1 N HCl (pH 1.2) and phosphate buffered saline (pH 7.4) to simulate acidic and alkaline release media respectively. The formulated microspheres were white, almost spherical in shape with some of the batches being free-flowing. Particles having a mean diameter in the range of 350 to 460 μm were obtained. The particle size distribution was polydisperse and was influenced by varying polymer-polymer ratios. The drug entrapment efficiency varied between 58.45-63.7 % while percent mucoadhesion in the range of 80 to 100 % was recorded. A slow release of ibuprofen from the microspheres occurred in 0.1 N HCl, while in phosphate buffered saline, higher amounts of the drug were released. Release of ibuprofen was found to be diffusion controlled and influenced by the drug - polymer ratio and the relative proportions of the two polymers in the formulation. The results from this study indicate that microspheres based on a co-polymer of Eudragit^® RS100 and RL100 could serve as a promising delivery vehicle for ibuprofen when the goal is to minimize the gastro-erosive adverse effects of the drug.

Keywords: microspheres, ibuprofen, co-polymer, Eudragit, release profile, swelling

Journal of Pharmaceutical and Allied Sciences, Vol. 7 No. 3 (2010)