Neuromuscular blockers:

Background Train of four
Pharmacokinetic Profiles  
Atracurium (Tracrium ® ) Cisatracurium (Nimbex ® )
doxacurium (Nuromax ® ) mivacurium (Mivacron ® )
pancuronium (Pavulon ® ) Rocuronium (Zemuron ® )
Succinylcholine vecuronium (Norcuron ® )
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Background  top of page

Overview: Neuromuscular blocking agents are used in the ICU setting for 3 reasons: (1) to eliminate spontaneous breathing and promote mechanical ventilation (eg eliminate urge to fight the vent. (2) Cause a pharmacologic restraint so patients do not harm themselves. (3) To decrease oxygen consumption.

Train of four:   top of page

Whenever a paralytic agent is used, the Train of Four is the test used to measure the degree of neuromuscular blockade. A peripheral nerve stimulator is used. Do a baseline measurement before paralytic agent is started to determine current necessary to obtain twitch. 20 mA may be enough for the patient. Complete and document until TOF to 2/4.


1. Attach 2 electrodes along the course of the ulnar nerve. (Temporal may be used.)
2. Connect the lead to the peripheral nerve stimulator by inserting the jacks into the Proximal (red) and Distal (black) output jacks. Connect the other end to the patient electrodes.
3. Turn the stimulator on. Select the current necessary (usually 20) for that patient to twitch when the stimuli is applied.
4. Press TOF once. It will deliver a train of four pulses where each is 0.5 seconds apart. Do NOT use the other buttons on the stimulator!
5. Count the number of twitches the patient had out of four (0/4, 1/4, 2/4, 3/4, 4/4.) Adjust the medication as ordered. Goal is 1/4 to 2/4 twitches.

Atracurium (Tracrium ® )  top of page

May be given undiluted by IV bolus.
Dosing (Adults): initially 0.4 to 0.5 mg/kg IV bolus, followed by 0.08 to 0.1 mg/kg every 20 to 45 minutes after initial dose.
Continuous infusion
: initially 0.4 to 0.5 mg IV bolus, followed by 9 to 10 mcg/kg/min. Maintenance infusion rates of 5 to 9 mcg/kg/min are usually adequate. (Range: 2 to 15 mcg/kg/min).

Toxic metabolite (laudanosine) may accumulate in renal failure.

[Supplied: 50 mg/5 ml ; 100 mg/10ml vial]

Cisatracurium  (Nimbex ® )  top of page

Dosing (Adults):
: initial dose: 0.15 to 0.2 mg/kg IV bolus followed by 0.03 mg/kg IV every 40 to 60 minutes.
Continuous infusion: 0.15 to 0.2 mg/kg IV bolus followed by 1 to 3 mcg/kg/min. The average infusion rate for long term use in the ICU is @ 3 mcg/kg/min (range: 0.5 to 10.2 mcg/kg/min). In some cases, re-administration of the bolus dose may be req'd while titrating. Dosage reductions are not required in renal or hepatic failure.

Drug of choice in the following cases: (1) hemodynamically significant increases in HR (eg >20%) while paralyzed with pancuronium or MAP>110. (2) Concurrent corticosteroid administration (>72hrs) (3) Significant renal dysfunction (CRCL < 30 ml/min) (4)History of asthma or bronchospasm.

doxacurium  (Nuromax ® )  top of page

Dosing (Adults): (usual)
Anesthesia adjunct
: initial, 0.05 mg/kg and 0.08 mg/kg IV to provide neuromuscular block for an average 100 min and 160 min, respectively. Maintenance, 0.005 mg/kg and 0.01 mg/kg IV to provide neuromuscular blockage for an average of 30 min and 45 min, respectively.
Endotracheal intubation: 0.05 mg/kg IV. Endotracheal intubation: (with succinylcholine) initial, 0.025 mg/kg IV.

[ Supplied: 1 mg/ml Solution]

mivacurium  (Mivacron ® )  top of page

Short-acting arizing neuromuscular blocking agent.
Dosing (Adults)
Endotracheal intubation: 0.15 mg/kg IV bolus. For extended neuromuscular block, IV average infusion rates of 6 to 7 mcg/kg/min are used. Recovery from muscular paralysis occurs within 15 to 30 minutes.

pancuronium  (Pavulon ® )  top of page

Non-depolarizing skeletal muscle blocker--competes with acetylcholine at the neuromuscular junction.
Dosing (Adults)
Intermittent dosing: 0.1 to 0.2 mg/kg (usually 0.1) every 1 to 3 hours (range: 0.04 to 0.2 mg/kg).
Continuous infusion: Loading dose: 0.04 to 0.10 mg/kg , followed by 1 to 1.7 mcg/kg/min or 0.06 to 0.1 mg/kg/hr

Rocuronium  (Zemuron ® )  top of page

Dosing (Adults)  (usual): Intubation(rapid sequence intubation): initial, 0.6-1.2 mg/kg IV. tracheal intubation: initial, 0.6 mg/kg IV. Maintenance, 0.1-0.2 mg/kg IV repeated as needed.
Maintenance (continuous IV infusion)
: 0.01-0.012 mg/kg/minute.
Skeletal muscle relaxation: initial, 0.6 mg/kg IV. Maintenance: 0.1-0.2 mg/kg IV repeated as needed. Alternatively: maintenance (continuous IV infusion): 0.01-0.012 mg/kg/minute

Succinylcholine   top of page

Depolarizing skeletal muscle blocker. Indications: procedures of short duration such as endotracheal intubation.
Dosing (Adults)
: 0.6 mg/kg (0.3 to 1.1) over 10-30 seconds, up to 150mg total dose. Maintenance: 0.04 to 0.07 mg/kg every 5-10 minutes as needed.
Continuous infusion: 2.5 mg/min (0.5 to 10 mg/min).
D Dilute to 1-2 mg/ml.

vecuronium  (Norcuron ® )  top of page

Dosing (Adults)
Intermittent dosing: initially 0.08 to 0.1 mg/kg IBW IV bolus. (Higher initial doses-up to 0.3 mg/kg-may be used for rapid onset. Maintenance: 0.01 to 0.015 mg/kg every 25 to 45 minutes as needed.

Continuous infusion: initial IV bolus (0.08 to 0.3 mg/kg), followed by (after 20-40min), 1 mcg/kg/min infusion (usual range: 0.8 to 1.2 mcg/kg/min).

Dosage reductions are not req'd in renal failure.

Pharmacokinetic Profiles  top of page


Neuromuscular Blocking Agents

Agent Onset
 of action
 of action
Short Acting
2.5 min 15 - 20 min 0.07
Mean: 90 seconds
(35 - 219 sec)
Mean: 15 min
(6 - 30 min)
1 - 3 min 31 min
(15 - 85 min)
Succinylcholine 30 - 60 seconds 5 - 8 min 0.3
Intermediate acting
2.5 - 5 min 20 - 45 min 0.2
2 - 3 min 30 - 40 min 0.05
2 - 3 min 60 - 90 min 0.06
2 - 3 min 25 - 40 min 0.05
Long Acting
6 min
(2.5 - 13)
100 min
(39 - 232)
2.5 - 5 min 75 min
(35 - 175)
Tubocurarine 3 - 5 min 70 - 90 min 0.05

ED90-95  = Dose required to produce 90-95% suppression of muscle response


Listed dosages are for - Adult patients ONLY. PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER. GlobalRPH does not directly or indirectly practice medicine or provide medical services and therefore assumes no liability whatsoever of any kind for the information and data accessed through the Service or for any diagnosis or treatment made in reliance thereon.

David F. McAuley, Pharm.D., R.Ph.  GlobalRPh Inc.
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