Emerging nanoparticulate systems: Preparation techniques and stimuli responsive release characteristics

Nanotechnology has become an outgrowing field in novel drug delivery system. It confers several merits over conventional formulations like increased solubility and bioavailability, targeted drug delivery and a decreased dose of the drug. The selection of appropriate method for the preparation of nanoparticulate system depends on the physicochemical characteristics of the drug to be loaded and polymer. This review has covered the most widely acceptable preparation techniques for polymeric and lipidic nanoparticles including nanoprecipitation, milling, extrusion, supercritical fluid technology, salting out, gelation, sonication, high-pressure homogenization, and solvent emulsification methods. Nanocarriers, the traditional nano-formulation drug delivery systems, encountered some major problems in process scale-up, reproducibility, and stability during storage. To circumvent these problems a new approach has emerged which are "In situ or self-assembled nanoparticles drug delivery system." Such approaches comprise experimentation with different types of polymers, surfactants or novel process in order to prepare a preconcentrate of drug formulation, which on entering into an aqueous medium (gastrointestinal fluid, blood) will form nanoparticles. The in situ nanoformulations can be the futuristic approach in nanocarriers to overcome the problems associated with the scale-up process and also minimize the cost of production. This review focuses on different preparation techniques for polymeric and lipidic nanocarriers preparation, in situ nanoformulation approaches and release characteristics of stimuli responsive nanoformulation.