sulfobutyl

Sulfobutyl refers to a sulfonated butyl ether substituent, typically described as an O-(CH2)3-SO3− group. The sulfonate imparts a negative charge and high water solubility, often used to increase solubility and modify the properties of larger molecules to which it is attached. In many contexts, sulfobutyl groups are introduced as ether substituents on sugars or other core structures to create sulfobutyl ether derivatives.

The most familiar example is sulfobutyl ether beta-cyclodextrin (SBE-β-CD), a widely used pharmaceutical excipient. SBE-β-CD is produced by reacting beta-cyclodextrin with 1,4-butane sultone to form sulfobutyl ether substitutions on the glucose units. The resulting material is a heterogeneous mixture with varying degrees of substitution, but all carry the hydrophilic sulfobutyl groups that enhance aqueous solubility. This modification preserves the cyclodextrin cavity's ability to form inclusion complexes with hydrophobic drugs, while increasing overall solubility and formulation versatility.

Applications and uses: sulfobutylated cyclodextrins, especially SBE-β-CD, are used to solubilize poorly water-soluble drugs and to stabilize labile compounds in both oral and injectable formulations. They can improve drug solubility, stability, and bioavailability, and are employed in intravenous formulations to enable higher drug loading and more consistent delivery. As pharmaceutical excipients, they are evaluated for safety and compatibility in each product, with regulatory considerations guiding their permitted usage levels and routes of administration.

In summary, sulfobutyl denotes a sulfonated butyl ether substituent that, when attached to cyclodextrins, creates effective solubilizing excipients such as SBE-β-CD for pharmaceutical use.