Rocuronium

Question 1

What is rocuronium?

Answer 1

Aminosteroid non-depolarising muscle relaxant

Question 2

What is the dose of rocuronium?

Answer 2

0. 6mg/kg - intubation in 90-120s
1. 9-1.2 mg/kg in 60s (duration 45mins)

Question 3

What temperature must rocuronium be stored at?

Answer 3

4 degrees celcius

Question 4

What is the metabolism and excretion of rocuronium?

Answer 4

• only 5% metabolised by liver
• excreted in bile (60%) and urine (40%)
• duration of action may be increased in liver/renal failure

Question 5

What are the uses of rocuronium?

Answer 5

• provide muscle relaxation to allow intubation, ventilation and surgery

Question 6

What is the absorption/distribution of rocuronium?

Answer 6

• 10% protein bound
• volume of distribution = 0.2 L/kg

Question 7

What is the MOA of rocuronium?

Answer 7

Competitive inhibition of ACh at nicotinic receptors at NMJ

Binds to alpha-subunit of receptor but does not stimulate it to open ion channel

Question 8

What are the SEs of rocuronium?

Answer 8

At high doses can exert vagolytic effect, causing tachycardia.

Otherwise no systemic effects.

Question 9

What are the chemical properties of rocuronium?

Answer 9

• monoquaternary amine analogue of vecuronium
• 7x less potent than vecuronium, so a higher dose needs to be given
• the higher number of molecules gives an increased concentration gradient between blood and NMJ so results in a faster onset of action by rules of kinetics

Question 10

What are the properties of the ideal neuromuscular blocking agent?

Answer 10

• cheap
• long shelf life at room temp
• no local/systemic SEs other than muscle relaxation
• short duration, suitable for infusion
• rapid metabolism to inactive products
• fast onset (1 circulation time)
• compatible with other drugs and solutions
• actions confined to NMJ
• antagonised by cholinesterase inhibitors
• not transferred across BBB or placenta

Question 11

What does the ACh receptor look like?

Answer 11

• Integral membrane protein found on post-synaptic membrane of the NMJ
• ligand-gated ion channel
• opens pores with ACh binds
• 5 subunits - 2 alpha, 1 beta, 1 delta, 1 gamma/epislon arranged round a central pore - nonspecific ion channel
• Na/K/Ca flow through pore in direction of concentration gradient
• when threshold depolarization is reached - voltage gated Na channels open, action potential is propagated