ABSTRACT: Succinylcholine (Sch) is the only depolarizing neuromuscular blocking agent widely used for rapid sequence induction in emergency rooms. Unfortunately, a variety of (sometimes lethal) adverse effects, such as hyperkalemia and cardiac arrest, are associated with its use, and currently there are no specific antidotes to reverse Sch or to treat these side-effects. Methods: The binding behaviors of Sch and several synthetic receptors, including cucurbit[7]uril, sulfo-calix[4]arene and water-soluble carboxylatopillar[6]arene (WP[6]), were first investigated. With a mouse model, a leathal dose of Sch was selected for evaluation of the antidotal effects of these synthetic receptors on Sch induced mortality. The antidotal effects of a selected synthetic receptor, WP[6], on Sch induced cardiac arrhythmias, hyperkalemia, rhabdomyolysis and paralysis were subsequently evaluated with rat and mouse models. The reversal mechanism was also investigated at a cellular level. Results: All of these macrocyclic molecules exhibited relatively high binding affinities with Sch in vitro. In a Sch-overdosed mouse model, immediate injection of these synthetic receptors right after Sch administration increased the overall survival rate, with WP[6] standing out with the most effective antidotal effects. In addition, administration of WP[6] also reversed the paralysis induced by Sch in a mouse model. Moreover, infusion of WP[6] to Sch-overdosed rats reduced the incidence of cardiac arrhythmia, inhibited the otherwise abnormally high serum potassium levels, and relieved the muscular damage. At the cellular level, WP[6] reversed the Sch induced depolarization and reduced the efflux of intracellular potassium. Conclusion: Synthetic receptors, particularly WP[6], exhibited high binding affinities towards Sch, and presented a significant potential as supramolecular therapeutics to treat the various side effects of Sch by specifically sequestering Sch in vivo.
