Cyclodextrins in drug delivery systems

Cyclodextrins are one of the most versatile aids in pharmaceutical technology, being of interest for the formulation of a wide range of delivery devices from the most classical dosage forms to the newest drug carriers. Their unique structural conformation together with the variety of substituents which can replace some of their hydroxyl groups endow cyclodextrins with versatile physicochemical features and the ability to form inclusion complexes with a wide range of drugs and macromolecules. Better knowledge of the reactivity of the cyclodextrins on forming supramolecular structures with a variety of architectures (self-assembled systems, poly(pseudo)rotaxanes, cross-linked networks, drug-conjugates) makes it possible to use cyclodextrins not only as drug solubilizers but also as true delivery systems. This review aims to summarize examples of the performance of cyclodextrins mainly in solid and semi-solid drug delivery systems, from the macro to the nanoparticulate scale, focusing on the information reported over the last 15 years.