Cyclodextrin-based controlled drug release system

Because of their bioadaptability and multi-functional characteristics, cycl odextrins (CDs) are capable of alleviating the undesirable properties of dr ug molecules in various routes of administration through the formation of i nclusion complexes. This article outlines the current application of natura l and chemically modified CDs in the design of advanced dosage forms. In an oral drug delivery system (DDS), the hydrophilic and ionizable CDs can ser ve as potent drug carriers in the immediate release- and delayed release-fo rmulations respectively, while the release rate of water-soluble drugs can be retarded by hydrophobic CDs. Since CDs are able to extend the function o f pharmaceutical additives, the combination of molecular encapsulation with other carrier materials will become effective and a valuable tool in the i mprovement of drug formulation. Moreover, the most desirable attribute for the drug carrier is its ability to deliver a drug to a targeted site; conju gates of a drug with CDs can be a versatile means of constructing a new cla ss of colon-targeting prodrugs. On the basis of this knowledge, the advanta ges and limitations of CDs in DDS are addressed. (C) 1999 Elsevier Science B.V. All rights reserved.