What is the mechanism of action of sugammadex, and which agents does it reverse?

• A. A γ-cyclodextrin that encapsulates rocuronium and vecuronium to terminate their effect
• B. Acetylcholinesterase inhibition reversing all neuromuscular blockers
• C. A monoclonal antibody that neutralizes rocuronium
• D. A calcium channel blocker used to terminate neuromuscular blockade

Answer: (A)

Sugammadex works by encapsulating certain steroidal nondepolarizing neuromuscular blockers. It is a γ-cyclodextrin derivative that forms a tight, water-soluble 1:1 complex with rocuronium and vecuronium, effectively removing them from the circulation and the nicotinic receptors. By sequestering the drug, the free concentration drops, allowing the previously blocked receptors to resume normal transmission and muscles to regain strength rapidly, even after deep blockade. This mechanism is specific for rocuronium and vecuronium (with limited activity on other steroids like pancuronium) and does not affect depolarizing blockers such as succinylcholine or non-steroidal agents like benzylisoquinolinium compounds. It is not an acetylcholinesterase inhibitor, nor a monoclonal antibody, nor a calcium channel blocker.