ESRD and Neuromuscular Blockade

Many drugs use the kidney as a final means of elimination, and the neuromuscular blockers commonly used today are no exception. All neuromuscular blocking agents are ionized to some degree, and are thus water soluble, so one might expect they would need an intact glomerulus (and therefore normal renal function) to be filtered and excreted. However, the glomerulus only excretes the free form of the compound, not the protein bound portion. To complicate things, some NMBs are not extensively protein bound, and the equilibration between bound and unbound is very rapid, making protein binding of mild importance in renal excretion and elimination in many of these drugs¹. Other methods of elimination include plasma redistribution, hepatic metabolism, and biliary excretion.²

Rocuronium:

Elimination half-time is increased by 37%; however, due to increased volume of distribution and plasma clearance in CRF, the duration of action is not significantly prolonged.

Vecuronium:

Elimination half-time increased by 25-5-%. More extensively metabolized hepatically than rocuronium. Duration of action may be prolonged, but is highly variable. Remember that Vecuronium has a metabolite that is 80% as potent as Vecuronium.

Pancuronium:

Nearly 100% eliminated by the kidney. Elimination half-time greatly prolonged.

Cisatracurium:

Eliminated by Hoffman elimination. Duration of action is not prolonged.³