Cyclodextrins as potential human anti-atherosclerotic agents : a comparative pilot study to determine the optimum route of administration of hydroxyl-propyl-ß-cyclodextrin (HP-ß-CD) in the apolipoprotein-E deficient 'knockout' mouse. Part II. Comparison of water, feed and intra-peritoneal delivery routes

Cyclodextrins (CDs) are a family of related molecules. They are naturally-occurring cyclic oligosaccharides (Figure 1). There are 3 main classes of CDs, α-cyclodextrins, ß-cyclodextrins, and ƴ-cyclodextrins containing 6, 7 and 8 glucose units respectively. The shape of the molecule three-dimensionally is rather like a 'doughnut'. The central 'hole' of the doughnut binds lipid-soluble molecules quite well, while the outer sur face is water-loving and so dissolves in water quite well. The size of the central hole (where drugs etc. bind) depends on the type of CD, being smallest in α-CDs and largest in ƴ-CDs. This size to some extent dictates what will bind to which type of CD. Because of the ability of CDs to form inclusion complexes (Figure 2) with other compounds (Rajewski and Stella, 1996) there is a lot of interest in the pharmaceutical industry in using them to deliver lipid-soluble drugs. There are lots of different types of chemical groups which can be attached to the glucose molecules to also vary the properties of the CD and many different CDs are now available commercially.