This paper discusses the development and validation of two analytical methods for the assay of naloxone in microparticles, as used in the therapy of opioid drug addiction (weaning). A UV-Vis spectrophotometric method is proposed to study drug loading and drug release, due to its ease and simplicity of performance, while a high performance liquid chromatographic method is developed as a means of stability-indication. Both analytical procedures were validated according to the International Committee for Harmonization (ICH) guidelines. Although the ranges and wavelengths were different for the two analytical methods, they were both found to be specific, linear, precise, and accurate under the determined conditions.