Sugammadex

Sugammadex

Which of the following statements regarding sugammadex is TRUE?

a) It is a modified α-cyclodextrin

b) The drug forms complexes with steroidal neuromuscular blocking drugs with a

ratio of 1:2

c) Following sugammadex administration to reverse rocuronium-induced

neuromuscular blockade the measured total plasma rocuronium concentration

will rise

d) The majority of the drug is metabolised and excreted by the kidneys

e) Sugammadex exerts its effect by binding with rocuronium at the neuromuscular

junction

Answer: c

Explanation

Sugammadex is a modified g-cyclodextrin of which there are three types (α, β and g) all

of which are doughnut shaped, have a hydrophobic, lipophilic cavity and a hydrophilic

exterior. To create sugammadex, g-cyclodextrin has been modified by the addition

of eight side-chains to extend the cavity and negatively charged carboxyl groups to

increase binding affinity. This has created a molecule that is able to bind with the

steroidal neuromuscular blocking drugs (rocuronium > vecuronium > pancuronium).

Sugammadex forms tight 1:1 complexes with these drugs in plasma, resulting in

movement of neuromuscular blocker away from the neuromuscular junction into the

plasma down a concentration gradient. Sugammadex has no effect on acetylcholinesterase

or any receptor system in the body. The majority of sugammadex is excreted

unchanged in the urine. For complete reversal of neuromuscular blockade to take place

sugammadex need only reduce post-synaptic receptor occupancy from 100% to 70%.

Several dose-finding studies have been carried out and suggested doses range between

2.0 to 4.0 mg/kg following reappearance of the second train-of-four twitch after

administration of rocuronium. There is also emerging evidence that sugammadex, at

a dose of 16 mg/kg, can promptly reverse high-dose rocuronium (1.0–1.2 mg/kg). This

may lead to the intriguing possibility of rocuronium challenging the place of suxamethonium

as the muscle relaxant of choice in rapid sequence induction.

Reference

Naguib M. Sugammadex: another milestone in clinical neuromuscular pharmacology.

Anesth Analg 2007; 104(3): 575–81.