Indomethacin-loaded microspheres: design and preparation by a multiple-emulsification technique and their in vitro evaluation.

A new oral controlled-release drug delivery system was developed with two polymers using a multiple-emulsification technique. Powdered drug was dispersed in methyl cellulose sol, which was emulsified in ethyl cellulose solution in ethyl acetate. The primary emulsion thus formed was reemulsified in aqueous medium. During this phase, discrete microspheres were formed under optimized conditions. The size distribution of the microspheres was investigated, and scanning electron microscopy revealed the surface topography of the microspheres. The in vitro drug release followed first-order diffusion-controlled dissolution. More than 85% of the drug was released over 6 hr at pH 6.2 for all dissolution batches.