This invention provide novel compositions, methods and devices for sustained drug delivery. The microencapsulated sustained drug delivery compositions are deposited using oscillating needle apparatus oscillating at 10-12000 minutes per minutes. The injected compositions may undergo variety of physical chemical changes upon deposition. The physical and chemical changes enables improved drug encapsulation and sustained drug release. Also described are new methods to form polymer microparticles or polymer films/implants in situ inside the tissue. The invention also describes colored biodegradable microparticle based compositions wherein the compositions comprise drug encapsulated microparticles and coloring agent encapsulated microparticles mixed in any proportion. Medical applications of the compositions and methods described in this invention are also described.