Use of thin film freezing to enable drug delivery: a review

Particle engineering may be used to improve the physicochemical properties of many new chemical entities to enhance the bioavailability. In "bottom up" technologies, particles may be formed by precipitation to control physicochemical properties including the particle size, surface characteristics, morphology, and crystallinity. This review provides an overview of various precipitation technologies used in pharmaceutical development, but highlights rapid freezing technologies, with emphasis on thin film freezing (TFF). In thin film freezing, the particle morphology may be controlled by manipulating the fluid dynamics and heat transfer properties upon spreading and freezing of liquid droplets on solid surfaces. Finally, in vitro and in vivo studies utilizing TFF are reviewed to emphasize the potential benefits of this technology in improving drug performance.