Nanosuspensions of poorly water soluble drugs prepared by top-down technologies

In recent years, nanosuspensions have been accepted as a valuable drug delivery system for poorly water-soluble drugs. Topdown and bottom-up technologies are the two main approaches for generating nanosuspensions. Several products manufactured by the top-down technologies have been successfully commercialized demonstrating that the processing features of the technologies are adaptable to industrial scale operation and meeting high pharmaceutical quality control standards. Nanosuspensions of poorly soluble drugs have shown to achieve dramatic improvements on the in vivo performance of the drugs including the enhancement of bioavailability and elimination of food effect when administered orally. This review will focus on the preparation of nanosuspensions by the top-down technologies. The influence of drug physicochemical properties on the nanosuspension forming process and the subsequent conversion into a dry powder form will be discussed with proposed mechanisms. In addition, the criteria for selection of stabilizers will be reviewed. The characteristics of drugs and stabilizers as well as their interaction effects on the redispersion properties of a dry powder prepared from a nanosuspension will be highlighted. The different administration routes of nanosuspensions are also presented with their potential therapeutic benefits.