Battle of the Blockers: Time for a Peace Treaty

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Rachel Rafeq
Emergency medicine pharmacist and toxicology enthusiast. Trained in medication safety and I apply that to everything. I love photography and world schooling my kids.

The Pre-brief

Most of the blog posts out there and the literature published seem to set “roc” and “sux” on the battlefield for the victory of being the best neuromuscular blocker but I would argue that each has unique attributes that are more desirable in different situations.

Mechanism of Action

  1. Neuromuscular blockers (NMB) are designed to facilitate endotracheal intubation, surgery or mechanical ventilation. 
    1. Succinylcholine: depolarizing NMB that produces depolarization of the motor endplate at the myoneural junction, which causes sustained flaccid skeletal muscle paralysis.
    2. Rocuronium: non-depolarizing NMB that blocks acetylcholine from binding to receptors on the motor endplate inhibiting depolarization.


Both provide a similar paralytic effect however the key is that Rocuronium is long-acting and Succinylcholine is short-acting.

Pharmacokinetics Myth Busting

Both rocuronium and succinylcholine provide safe and efficacious neuromuscular blockade however, succinylcholine, historically has been deemed a superior choice due to its perceived quicker onset of action. What providers should know is that Rocuronium has dose-dependent kinetics and therefore depending on the dose you are able to achieve a faster onset.


The National Emergency Airway Registry Study (NEARS) published in 2018 compared first pass intubation success and adverse event rates between succinylcholine and rocuronium. Data was analyzed from the national emergency airway registry

Results were similar even when NMB weight based doses were stratified. Ultimately, there was no association between the NMB selected and first pass RSI success or in subsequent adverse events.

The following year, Guihard and colleagues published the first randomized control trial comparing rocuronium and succinylcholine in an emergency setting.7 They assessed the noninferiority of rocuronium vs succinylcholine in first attempt endotracheal intubation success during out of hospital emergencies. This was a multicenter, single blinded noninferiority randomized control trial that included 610 subjects in rocuronium 1.2 mg/kg arm against 616 subjects in the succinylcholine 1 mg/kg arm.  Noninferiority margin was set to 7%. Ultimately, the team was unable to demonstrate non inferiority of rocuronium compared to succinylcholine




Succinylcholine is associated with a greater number of adverse events than rocuronium.

Selecting the Most Appropriate Paralytic

Selecting the optimal NMB comes down to a few factors. 

  1. Induction agent choice 
    1. When using etomidate, consider succinylcholine over rocuronium. Etomidate lasts 3-5 minutes. If rocuronium is used, the patient will remain paralyzed long after etomidate wears off, unlike succinylcholine which is similar we know that inadequate pain and sedation can increase catecholamine activity, leading to increased risk of myocardial ischemia and infarction. 
      1. “But we never delay analgesia and sedation!” you say, however, unless you have these medications directly stocked in your patient care area, and available without a physician order or pharmacist verification, there will be delays.
    2. If Rocuronium is your planned paralytic, consider using a longer-acting agent like Ketamine.
  2. The patient is being intubated due to a lack of seizure control
    1. With succinylcholine’s shorter duration of action, it allows for neurologic assessment to be performed sooner than compared to rocuronium. 
  3. Contraindications to Succinylcholine
    1. Patients with hyperkalemia or malignant hyperthermia would benefit from rocuronium. 
  4. Unidentified patients
    1.  Patients in which we do not have any medical history and therefore cannot confirm the contraindications to succinylcholine would benefit from rocuronium.
  5. Lab work is unavailable 
    1.  If lab work is unavailable and we cannot rule out the risk of hyperkalemia, consider rocuronium.

The Debrief

  1. Neuromuscular agents provide no sedation or analgesia and therefore adequate sedation and analgesia should be administered before and after administration 
  2. At higher doses of 1-2 mg/kg, rocuronium has a similar onset of action as succinylcholine (60 seconds); however rocuronium will last for 30-60 minutes compared to succinylcholine, which lasts 5-15 minutes. 
  3. Consider appropriate induction agents that have durations similar to the neuromuscular agent that is being utilized
  4. Succinylcholine may be an ideal agent compared to rocuronium for patients who are being intubated post seizure event
  5. Rocuronium may be an ideal agent compared to succinylcholine in patients where risk of hyperkalemia, malignant hyperthermia, increased intraocular and intracranial pressure exist. 
  6. Rocuronium may also be an ideal agent in patients whose history is unknown or whose lab work is unavailable. 


    1. Anectane® (succinylcholine) [package insert]. Princeton, NJ: Sandoz Inc; December 2020
    2. Rocuronium [package insert]. Irvine, CA; Teva Pharmaceuticals; December 2020
    3. Johnson EG, Meier A, Shirakbari A, Weant K, Baker Justice S. Impact of Rocuronium and Succinylcholine on Sedation Initiation After Rapid Sequence Intubation. J Emerg Med. 2015;49(1):43-49. doi:10.1016/j.jemermed.2014.12.028 
    4. Xue FS, Liao X, Tong SY, Liu JH, An G, Luo LK. Dose-response and time-course of the effect of rocuronium bromide during sevoflurane anaesthesia. Anaesthesia. 1998;53(1):25-30. doi:10.1111/j.1365-2044.1998.00278.x 
    5. Heier T, Caldwell JE. Rapid tracheal intubation with large-dose rocuronium: a probability-based approach. Anesth Analg. 2000;90(1):175-179. doi:10.1097/00000539-200001000-00036 
    6. April MD, Arana A, Pallin DJ, et al. Emergency Department Intubation Success With Succinylcholine Versus Rocuronium: A National Emergency Airway Registry Study. Ann Emerg Med. 2018;72(6):645-653. doi:10.1016/j.annemergmed.2018.03.042Magorian T, Flannery KB, Miller RD. Comparison of rocuronium, succinylcholine, and vecuronium for rapid-sequence induction of anesthesia in adult patients. Anesthesiology. 1993;79(5):913-918. doi:10.1097/00000542-199311000-00007
    7. Guihard B, Chollet-Xémard C, Lakhnati P, et al. Effect of Rocuronium vs Succinylcholine on Endotracheal Intubation Success Rate Among Patients Undergoing Out-of-Hospital Rapid Sequence Intubation: A Randomized Clinical Trial. JAMA. 2019;322(23):2303-2312. doi:10.1001/jama.2019.18254 


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