Cucurbit[7]uril host−guest complexations of steroidal neuromuscular blocking agents in aqueous solution

The complexations of three steroidal neuromuscular blocking agents, rocuronium, vecuronium, and pancuronium, by the cucurbit[7]uril host molecule have been investigated in aqueous solution using 1H NMR spectroscopy and ESI mass spectrometry. The CB[7] binds to each of the two terminal cationic N-heterocyclic groups by means of ion-dipole interactions and hydrophobic effects, with stability constants in the order of vecuronium > pancuronium > rocuronium. This trend is different from those observed for the anionic substituted γ-cyclodextrin (Sugammadex), currently employed as a neuromuscular blockade reversal agent, and an acylic glycoluril tetramer (Calabadion), recently reported to reverse both steroidal and benzylisoquinolium neuromuscular blocking agents in rats.