Faculty of Pharmaceutical Sciences, University of Iceland, Hagi, Hofsvallagata 53, IS-107 Reykjavik, Iceland.
Int J Pharm. 2010 Mar 15;387(1-2):199-208. doi: 10.1016/j.ijpharm.2009.11.035. Epub 2009 Dec 4.
Cyclodextrins (CDs) are widely used as enabling pharmaceutical excipients, mainly as solubilizing complexing agents. CDs are cyclic oligosaccharides with hydrophilic outer surface and a somewhat lipophilic central cavity. In aqueous solutions CDs are able to solubilize lipophilic drugs by taking up some lipophilic moiety of the drug molecule into the central cavity, i.e. through formation of hydrophilic inclusion complexes. Recently it has been observed that that other types of CD complexes, such as non-inclusion complexes, are also participating in the CD solubilization of poorly soluble drugs. However, in aqueous solutions CDs are also able self-assemble to form nanosized aggregates that can contribute to their solubilizing properties. At low CD concentrations (at about 1%, w/v) the fraction of CD molecules forming aggregates is insignificant but the aggregation increases rapidly with increasing CD concentration. Also, formation of CD complexes can increase the tendency of CDs to form aggregates and can lead to formation of micellar-type CD aggregates capable to solubilize poorly soluble compounds that do not readily form inclusion complexes. In this article formation of CD aggregates and CD nanoparticles is reviewed with emphasis on the physicochemical properties of self-assembled CDs and CD complexes.
环糊精（CDs）广泛用作赋形剂药物辅料，主要用作增溶络合剂。CDs 是具有亲水外表面和略微亲脂性中心腔的环状低聚糖。在水溶液中，CD 能够通过将药物分子的一些亲脂部分带入中心腔，即通过形成亲水性包合物，来增溶亲脂性药物。最近观察到，其他类型的 CD 配合物，如非包合物配合物，也参与了难溶性药物的 CD 增溶作用。然而，在水溶液中，CD 也能够自组装形成纳米尺寸的聚集体，从而有助于其增溶性质。在低 CD 浓度（约 1%，w/v）下，形成聚集体的 CD 分子分数可以忽略不计，但随着 CD 浓度的增加，聚集迅速增加。此外，CD 配合物的形成会增加 CD 形成聚集体的趋势，并导致形成胶束型 CD 聚集体，从而能够增溶不易形成包合物的难溶性化合物。本文综述了 CD 聚集体和 CD 纳米颗粒的形成，重点介绍了自组装 CD 和 CD 配合物的物理化学性质。
