Recently, risperidone was encapsula

Recently, risperidone was encapsulated into PLGA micropar- ticles by an o/w emulsion technique that employed methyldichloroacetate in place of the traditional volatile carrier solvent to dissolve the polymer. By the addition of an ammonia solu- tion the solvent was hydrolyzed into water-miscible products, i.e., methanol and dichloroacetamide, resulting in the precipitation of PLGA (Sah and Lee, 2006). Although the encapsulation effi- ciency was almost 100% for risperidone, the flux of methanol from the microparticle core to the water phase may result in a loss of methanol-soluble drugs. This theory is supported by a study, where the encapsulation efficiency of progesterone was as much as 15% lower when ammonolysis with methyl chloroacetate was compared to a standard encapsulation method with methylene chloride (Kim et al., 2007). In the preliminary studies, methyl dichloroacetate resulted in particle aggregation during vacuum drying and neither release nor precise gas chromatographic resid- ual solvent analysis were provided as methyl dichloroacetate and methyl chloroacetate (Pohanish and Greene, 1996; USCG, 1999), like numerous traditionally used solvents for encapsulation, are toxic.