Cyclodextrins in Drug Delivery Systems and their Effects on Biological Barriers

Cyclodextrins are widely used excipients, composed of glucopyranose units with a cyclic structure. One of their most important properties, is that their inner cavity is hydrophobic, while their surface is hydrophilic. This enables them for the complex formation with lipophilic molecules. They have several applications in the pharmaceutical field like solubility enhancers or the building blocks of larger drug delivery systems. On the other hand, they have numerous effects on cells or biological barriers. In this review the most important properties of cyclodextrins and cyclodextrinbased drug delivery systems are summarized with special focus on their biological activity. Download the full MDPI publication here: Cyclodextrins in Drug Delivery Systems and their Effects on Biological Barriers

Introduction

Cylodextrins are cyclic, non-reducing oligosaccharides composed of glucopyranose units [1]. The α-, β-, and γ-cyclodextrins are widely known, which contain 6, 7, and 8 units respectively. Recently the smallest cyclodextrins were synthetized, containing 3 and 4 glucopyranose units [2], and on the other hand big oligosaccharides with more, than 8 units are also known [1] and applied for complexation [3] or as chiral selectors for enantiomeric pharmaceuticals [4]. Glucopyranose units form a conical cylinder, which has a hydrophobic inner cavity and a hydrophilic outer surface. This structure enables them to form inclusion complexes with hydrophobic molecules. In general, the complex forming abilities of α-, β-, and γ-cyclodextrins are better, than the larger ones, thus these derivatives are practically important [1].

Cyclodextrin rings can be chemically modified, linked with substituents or other cyclodextrin rings and used to build up larger nanostructures. The type and application of these nano-constructs is continuously increasing. Besides the drug complexation, cyclodextrins can form complexes with natural, biological important molecules like phospholipids, cholesterol or other lipophilic molecules. It causes various effects, especially at cellular level or on biological barriers. On the other hand, cholesterol complexation properties of hydroxypropyl-β- cyclodextrin is applied in the treatment of Niemann Pick Disease Type C (NPC) and was approved as an orphan drug. This mini-review gives a summary on the basic complexation, drug delivery and biological properties of cyclodextrins and the cyclodextrin-based nano-scale drug delivery systems.

Download the full MDPI publication here: Cyclodextrins in Drug Delivery Systems and their Effects on Biological Barriers

Ádám Haimhoffer, Ágnes Rusznyák,  Katalin Réti-Nagy,  Gábor Vasvári, Judit Váradi,
Miklós Vecsernyés, Ildikó Bácskay, Pálma Fehér, Zoltán Ujhelyi and Ferenc Fenyvesi

Sci. Pharm. 2019, 87, 33; doi:10.3390/scipharm87040033