Rifampicin-carrying poly(D,L-lactide) microspheres: loading and release

Rifampicin-loaded poly(D,L-lactide) (PDLLA) microspheres in the size range of 0.8-8.0 microns were prepared by a modified solvent evaporation method. Rifampicin loading was changed by using different types of solvents (i.e. methylene chloride, chloroform, and carbon tetrachloride) with different solvent/polymer ratios and different emulsifiers (i.e. methyl cellulose, gelatin, and Tween-20), and by changing the initial drug/polymer ratio. These rifampicin-loaded PDLLA microspheres degraded much faster in the medium at basic pH (9.8) and at high temperatures (55 degrees C). Rifampicin release was also high under these conditions. It was concluded that rifampicin release was both degradation- and diffusion-controlled.