Succinylcholine: An Anesthetist’s View-Guest Blogger

20 Sep

As an Anesthetist for far too many years, let me tell you why succinylcholine is such a perfect murder weapon.

The best poisons usually have three things in common: small effective dose, also called Median Lethal Dose (or LD50), ease of administration, and rapid and definitive action. The fourth characteristic, the difficulty in detection by a forensics team is a big premium that most poisons don’t posses. Most poisons, that is, except succinylcholine and maybe a few others. Forensic scientists please correct me if I’m wrong.

A quick review of pharmacology shows succinylcholine is a muscle relaxant. Anesthesiologists and Nurse Anesthetists (CRNA’s) call it “sux”. Sux is commonly used before intubations, as it completely relaxes patients’ muscles and facilitates intubation of the trachea with an endotracheal tube. Sux is a rapidly acting depolarizer that can be given intravenously (IV) or intramuscularly (IM). Once administered, succinylcholine circulates in the blood, reaches nicotinic receptors on the surface of muscle cells, and there it imitates the action of acetylcholine, a neurotransmitter that our nerves naturally release to make our muscles move. When succinylcholine is given, seconds later the patient fasciculates, and all muscles in his body become depolarized. In essence, sux makes every muscle twitch to the point that it becomes unresponsive to any subsequent stimulation: you can’t breathe, you can’t even blink.

Sux is highly effective. In IV form, 100 mg of sux will depolarize every muscle in the body of a 70kg man in about 30-45 seconds. And the patient will not be able to take another breath for at least 5 minutes. So without assisted ventilation, he is dead as quickly as three minutes. The IM dose of sux is not much different, but takes two to four times the IV dose and takes 3-5 minutes to begin working.

So there you have it: succinylcholine is an easy to inject poison, it is highly effective, and is guaranteed-to-work quickly to kill.

The fourth characteristic of succinylcholine is sux is almost impossible to detect because its metabolites are all naturally occurring molecules. It works this way. Most molecules of succinylcholine break down in blood into succinylmonocholine and choline, thanks to a circulating enzyme called pseudocholinesterase. The process is so efficient only a small fraction of sux molecules given actually reach neuromuscular junctions. Succinylmonocholine is then hydrolyzed into succinic acid, or succinate, a naturally occurring substance.

Succinate is famous because it is an important player in TCA (Krebs) cycle, a series of chemical reactions that powers all living cells that use oxygen.The entire human complex pinnacles on the oxygen molecule. Take it away and our body chokes up and dies.

Ruby Johnson, CRNA,Phd


32 responses to “Succinylcholine: An Anesthetist’s View-Guest Blogger

  1. Kate Ryan

    September 20, 2010 at 9:57 am

    What happens if sux is ingested? Does it have any impact. Can a killer slip some in a drink or food and do them in that way?

    Also, is it easy to obtain? Especially if your would-be killer doesn’t work in a hospital or for a doctor? Any requirements to picking it up from, say, a distribution point?


    • D.P. Lyle, MD

      September 20, 2010 at 6:10 pm

      Sux must be injected to work so can’t be added to food. It can be stolen from a hospital OR or pharmacy or from a pharmacy. It can be purchased from surgical supply firms but is controlled fairly tightly.


  2. Doug

    September 20, 2010 at 7:42 pm

    If this medication was not detected, how would a coroner rule on the cause of death (for instance, an otherwise healthy person, no signs of trauma, who just appears to have stopped breathing)?


    • D.P. Lyle, MD

      September 21, 2010 at 7:33 am

      This med is often difficult or impossible to detect with any degree of reliability so sometimes the ME can’t determine the cause of death and could indeed write it off as a natural event.


  3. Ruby Johnson

    September 21, 2010 at 8:28 am

    I’m convinced that if someone wants to kill another human being, they can find the means to do it.
    While drug carts are now locked, there was a time when they weren’t and drug diversion was common among hospital workers. I am sure there are probably a few holdouts on locking carts, except when the Joint Commission on Hospitals or Medicare inspects the hospital. The pyxsis unit, a locked cart which is electronically hooked up to the main hospital pharmacy, has really prevented drug diversion to a great extent by hospital workers. You can’t get a drug out unless a prescription for the drug is sent to the pharmacy. That’s not to say that it can’t be done, it’s just harder to do, and not all hospitals have this unit.
    One thing, I’m not sure if EMT’s are required to account for drugs due to the nature of their work, but this would seem to be a place where diversion could occur.


    • Mary Welk

      September 21, 2010 at 12:19 pm

      I used sux in a short story called “Code Blue” in the Bleak House anthology CHICAGO BLUES. The setting was an ER, the victim a repeat sex offender, the perp an ER nurse who was sick of justice being trampled on by slick lawyers. I was an ER nurse at the time, and I know how nurses destroy any sux that’s left over after an intubation. About the only way you can steal it from a modern-day hospital is by pocketing the used vials and thus, whatever is left over in them. It’s almost impossible to get your hands on it any other way. As for EMTs, it’s not a drug approved for use in their SOPs (Standard Operating Procedures) in my state, and I doubt it’s approved in other states either due to its potency. If anyone wants to write a story where an EMT uses sux to commit murder, or the perp gets the drug from an EMT, the writer should check local EMT standards first.


      • Andrew Sims

        October 12, 2016 at 6:15 am


        Just to answer your post real quickly, I am a paramedic in Grenville County, SC and we use Succinylcholine as our paralyzing agent for RSI procedures (Rapid Sequence Induction). It is on Standing Orders, so we don’t even need online medical control for it. Not all agencies or counties allow this procedure and there are strict policies and procedures in place governing the particular use of this medication. For example, we can only use this medication in certain calls where airway control is needed, but we can’t intubate under normal conditions. An example would be a major stroke with unconsciousness and no airway control or perhaps a trauma patient with trismus that is unconscious and we need to intubate and control the airway. Even then, only certain paramedics here can perform the procedure. They must have been a medic for at least 2 years and pass both a written and practical test. Even then, they must maintain this “certification” through continuous in-service training, etc. Anyway, just wanted to let you know that there are places out there where Paramedics can use Succinylcholine on standing orders. Hope this helps.


  4. Karen

    November 20, 2011 at 9:35 pm

    But how long does it take for suxx to be excreted in urine? Ii am thinking of the Kathy Augustine case. I am also thinking since Ms. Augustine died in the hospital, could someone put it straight into a urine sample? There was only suxx in her urine and no place else.


    • D.P. Lyle, MD

      November 21, 2011 at 8:22 am

      Most of the Sux is very quickly converted to succinc acid and other breakdown products in the blood and these will begin to appear in the urine very quickly also. All forms of Sux testing–blood or urine, Sux itself or its breakdown products–is difficult and controversial.


  5. curious

    November 14, 2013 at 6:48 pm

    So how does a person die from Sux? by asphyxiation, cardiac arrest, other?


    • D.P. Lyle, MD

      November 14, 2013 at 6:51 pm

      It paralyzes all the muscles, including those used in breathing so the victim dies from asphyxia–wide wake the entire time–just not able to breath or move. Scary stuff.


  6. Mark Riley

    February 28, 2014 at 3:00 am

    Sux is probably a hard substance to get hold off unless you are in the medical profession


  7. Samrat Banerjee

    December 23, 2017 at 1:00 pm

    I have seen a movie where succinylcholine used with the water for a person and that victim get died within 5 minutes….. So, is it real that if sux mixing with a glass of water then a person can die to drink that water????


    • D.P. Lyle, MD

      December 24, 2017 at 6:19 am

      Likely that wouldn’t work. SUX must be injected to work fully and if ingested the drug would be destroyed by the stomach enzymes.


      • Samrat Banerjee

        December 25, 2017 at 2:07 pm

        Ok… So, that means this is fake to mixing with water……. A person do not die to drink that water which is sux mixed………. Right or wrong????


      • D.P. Lyle, MD

        December 25, 2017 at 3:00 pm

        Yes. Sux needs to be injected either IV or IM to be effective.


  8. Samrat Banerjee

    December 27, 2017 at 8:05 am

    Ok…. But, Sir if someone mix with water with a excessive high dose….. Then also it will not work???? I mean a person do not die????


  9. Samrat Banerjee

    December 27, 2017 at 9:43 am

    Ok….. Thank You very much Sir……..


  10. Samrat Banerjee

    December 27, 2017 at 10:24 am

    Sir, I am student of Criminology…….. I have a query that is there any ingested drug or poison in our society which can kill a person……. And which is also not identified in autopsy or postmortem????


  11. Samrat Banerjee

    December 28, 2017 at 4:12 am

    Is there any ingested drug which causes heart attack quickly………


    • D.P. Lyle, MD

      December 28, 2017 at 7:46 am

      No. There is no drug that relaibly causes a true heart attack.


      • Samrat Banerjee

        January 13, 2018 at 10:33 pm

        Is there any powder form of succinylcholine? If there then please tell me that what is the procedure to use it?


      • D.P. Lyle, MD

        January 14, 2018 at 6:12 am

        I decline to answer this question.


  12. Shantanu Jain

    February 2, 2019 at 12:01 pm

    Sir what are the various methods for detecting sux? Also what are their limitations? Which is the most effective and reliable method amongst them?


    • D.P. Lyle, MD

      February 2, 2019 at 12:25 pm

      Unfortunately, as far as I know, there is still no standardized way to detect SUX or succinic acid or its other breakdown products. Each method has issues and experts disagree on the accuracy of each one.


  13. Sachin Joshi

    February 7, 2019 at 3:28 am

    Dear Sir..I understand that IV and IM forms are the only ways to administer sux. But can it be used with DMSO which takes in everything in the blood stream upon skin contact? That way can sux be administered transdermally rather than through and injection?


    • D.P. Lyle, MD

      February 7, 2019 at 8:25 am

      That wouldn’t work.


      • Sachin Joshi

        February 7, 2019 at 9:00 am

        Thank you for the reply Sir. Wouldn’t that be equivalent to injecting it as that enters the blood stream as well? DMSO has the properties of penetrating all substances dissolved in it into the blood stream through the skin.


      • D.P. Lyle, MD

        February 7, 2019 at 9:07 am

        DMSO doesn’t do nearly as much as most folks think. And here it would make​ little difference. The SUX molecule isn’t built to pass through the skin barrier and adding something else won’t change that.


  14. Sachin Joshi

    February 7, 2019 at 9:17 am

    Thank you very much for your inputs and explanations Sir.



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