Cyclodextrins--enabling excipients: their present and future use in pharmaceuticals.

Cyclodextrins (CDs) complex hydrophobic drugs, increasing their aqueous solubility and stability. CD complexation enables the creation of formulations for water-insoluble drugs that are difficult to deliver with more traditional formulations. Currently, 10 pharmaceutical products are marketed as CD formulations. A CD-based formulation, like any other, is evaluated for quality and safety. The 6 CDs currently available for use in pharmaceutical products are alpha-, beta-, and gamma-CD and the methyl (M), hydroxypropyl (HP), and sulfobutylether (SBE) derivatives of beta-CD. The structural features of these CDs are evaluated for their affect on complexation performance. Optimal specifications, quality production, and safety of each CD is presented. The current and future regulatory process facing excipients is summarized, and the current regulatory status of the CDs in Japan, the United States, and Europe is presented.