Sulfobutylether-beta-cyclodextrin (SBE-β-CD)

Sulfobutylether-beta-cyclodextrin (SBE-β-CD) is a chemically modified, polyanionic cyclic oligosaccharide used primarily as a pharmaceutical excipient to enhance the solubility and stability of poorly water-soluble active pharmaceutical ingredients (APIs). It is composed of seven glucopyranose units with sulfobutyl ether groups substituted onto the hydroxyl groups, which significantly increases its aqueous solubility compared to parent beta-cyclodextrin. The molecule functions by creating a 'host-guest' relationship where a hydrophobic drug molecule is sequestered within its lipophilic internal cavity, while the charged exterior maintains the complex in solution. This technology is essential for the formulation of various intravenous and oral medications, allowing for the delivery of drugs that would otherwise be difficult to administer effectively. Commonly known by the trade name Captisol, SBE-β-CD is utilized in several FDA-approved therapies, including the antiviral remdesivir and the antifungal voriconazole. While it is biologically inactive and generally considered safe, it is primarily eliminated via glomerular filtration, which can lead to accumulation in patients with significant renal dysfunction. Consequently, clinicians must monitor renal function when administering drugs formulated with high concentrations of this excipient. It is not a therapeutic target in the traditional biological sense but rather a critical enabling component of modern drug delivery systems.

Other names

CaptisolSulfobutyl ether beta-cyclodextrinBetadex sulfobutyl ether sodiumSBE7-β-CDSulfobutylether-β-cyclodextrin

SBE-β-CD acts as a host molecule that forms non-covalent inclusion complexes with hydrophobic guest molecules. The lipophilic central cavity of the cyclodextrin encapsulates the poorly soluble drug, while the hydrophilic sulfobutyl ether groups on the exterior surface ensure high aqueous solubility and stability of the resulting complex in systemic circulation.