Neuromuscular Blocker Reversal Agents (ICU Drips)

Mechanism of Reversal

• Goal: Increase acetylcholine (ACh) at NMJ → outcompetes paralytic drugs.

• How: Inhibit acetylcholinesterase (AChE) → prevents breakdown of ACh → ↑ACh available.

• Effect: ACh displaces neuromuscular blockers from receptors → restores muscle function.

AChE Inhibitors (Reversal Agents)

• Neostigmine

• Pyridostigmine

• Edrophonium

Problem: ACh ↑ throughout body → excessive parasympathetic activation →

• Bradycardia, even asystole

• ↑Salivation

• Miosis (pupil constriction)

• Bronchoconstriction

• ↑Urine output

• ↑Peristalsis

Antimuscarinic (Anticholinergic) Agents (to counteract PSNS effects)

Given together with AChE inhibitors to prevent dangerous side effects.

• Scopolamine

  • Rarely IV (sedating)

  • Mostly transdermal patch (antiemetic use)

• Glycopyrrolate (Robinul) – Drug of choice

  • Does not cross BBB

  • Used to ↓secretions, prevent vagal bradycardia

  • IV onset ~1 min

• Atropine

  • Crosses BBB → CNS side effects, tachycardia

  • Not for secretion management

  • Used only in emergent bradycardia unresponsive to glycopyrrolate

  • IV onset ~45 sec

 Novel Agent: Sugammadex (Bridion®)

• FDA approval: 2015

• MOA: Directly binds aminosteroid NMBAs → prevents them from binding receptors

• Best for: Rocuronium (highest affinity), also vecuronium & pancuronium

• Ineffective for: Succinylcholine, atracurium, cisatracurium

• Onset: 2–4 min → complete reversal

• Limitation: Very expensive → not always first-line

Key Points

• AChE inhibitors ↑ACh everywhere → need antimuscarinic co-administration.

• Glycopyrrolate = safest/most commonly used adjunct.

• Atropine reserved for emergencies.

• Sugammadex = rapid, targeted reversal of aminosteroid paralytics, but costly.