Prolonged release of rifampicin from multiple w/o/w emulsion systems.

The formation of multiple w/o/w emulsions with improved stability by using interfacial complex films between polyvinyl alcohol, acacia, polyvinylpyrrolidone and sorbitan monooleate (Span 80) is described. The long term stability of the emulsions, as assessed by microscopy and particle size analysis, showed no changes in the w/o/w emulsion systems prepared using these macromolecules in the internal phase. It has also been observed that the release rate of rifampicin, contained in the internal phase, increased significantly on addition of calcium stearate and/or soya lecithin to the organic phase.