Abstract

Complexation is one of the several ways to enhance favorably the physicochemical properties of pharmaceutical compounds. It may loosely be defined as the reversible association of a substrate and ligand to form a new species. Although the classification of complexes is somewhat arbitrary, the differentiation is usually based on the types of interactions and species involved, for example, metal complexes, molecular complexes, inclusion complexes, and ion-exchange compounds. Cyclodextrins (CDs) are classic examples of compounds that form inclusion complexes. These complexes are formed when a “guest” molecule is partially or fully included inside a “host” molecule, for example, CD, with no covalent bonding. When inclusion complexes are formed, the physicochemical parameters of the guest molecule are disguised or altered, and improvements in the molecules solubility, stability, taste, safety, bioavailability, and so on are commonly seen.