Targeted Cyclodextrins.

Since 1970s cyclodextrins (CDs) and their derivatives, in virtue of their peculiar inclusion properties, have been proposed as pharmaceutical excipients and have found application in several marketed products. They are deemed unique products since natural and semi-synthetic CDs can modulate the physical, chemical and biopharmaceutical properties of guest molecules, eventually ameliorating critical drug properties such as water solubility, dissolution rate, stability and bioavailability. In addition, cyclodextrins have been studied as functional excipients in controlled release system. The advances in chemical strategies for CDs derivatization along with the exciting results obtained with site selective colloidal drug carriers, namely liposomes and nanoparticles, has brought to development of targeted cyclodextrins. In latest years, cyclodextrins have been regarded not only as simple functional excipients but rather as multifunctional supramolecular carriers. Two requirements have to fulfil to obtain such targeted CDs: 1. conjugation of targeting moieties on the CD scaffold, without impairing their specific recognition of cellular targets: 2. adequate complexation of the guest molecule that have to be efficiently transported to the specific disease site. In this chapter, a critical overview of some of the most interesting approaches aimed at develop targeted cyclodextrins is presented. Particular emphasis will be dedicated to tumor targeting, a field where selective treatments are strongly required and expectations from targeted therapies are extremely high. The chapter reviews also a number of other modified cyclodextrins developed as molecular carriers designed to attain tissues, organs and body districts where a more specific and efficient treatment is required. Taking into account the latest evolution of semi-synthetic cyclodextrins, the applications of targeted cyclodextrins will increase in the near future. The new opportunities offered by biotechnology, both in terms of biological targets and potent but fragile bioactive molecules, are expected to sustain the evolution in the pharmaceutical field with targeted delivery systems playing a pivotal role.