This page shows what was measured, who it was measured in, and what that does not settle.
What Succinylcholine does in the body
Paralysing the muscles for about five minutes so a breathing tube can be placed quickly in an emergency
The nerve normally tells a muscle to contract by releasing acetylcholine, which is destroyed within a millisecond so the muscle can reset. Succinylcholine is two of those molecules stuck together, and the enzyme at the junction cannot break it down. It switches the receptor on and holds it on. The muscle twitches once — the visible flicker anaesthetists call fasciculation — and then cannot respond again while the drug is there. The drug leaves quickly not because the muscle clears it, but because a different enzyme in the blood is chewing through it the entire time, so only a fraction ever arrives and it is drawn back out within minutes.
What happened in people
Superior to rocuronium for excellent intubating conditions across 50 randomised trials and 4,151 participants, risk ratio 0.86 (95% CI 0.81 to 0.92)
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
That an intubating-conditions advantage measured in elective patients settles the choice against rocuronium, when the harms driving that choice are rarer than the trials could detect
Where it acts
Postsynaptic membrane of the motor endplate, and the plasma compartment where the enzyme that destroys the drug lives
Kind of result
The kind of result is not recorded
Supervision
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · I9L0DDD30I · read 2026-08-29
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 154 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Comparator
A comparator is whatever the treatment was measured against.
A picture of it, and where the picture fails
It is like the other runner in a race.
Where that stops being true. A race has one winner. A study can show both arms improved.
What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.
The control condition against which the experimental intervention is assessed.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Excellent intubating conditions during rapid sequence induction
✓ The study showed what it set out to show
Who was studied
Tran Cochrane review of rocuronium versus succinylcholine for rapid sequence intubation
How many people
4151
Study design
Systematic review and meta-analysis of 50 randomised and controlled clinical trials
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Succinylcholine superior: risk ratio 0.86 (95% CI 0.81 to 0.92) for excellent conditions, 0.97 (95% CI 0.95 to 0.99) for clinically acceptable conditions, 0.81 (95% CI 0.73 to 0.88) with thiopental induction
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. No severe adverse outcomes were reported in any included trial. That is the central limitation: the harms that justify choosing rocuronium instead occur at frequencies these 4,151 patients could not have revealed.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Sterile aqueous solution for intravenous injection and infusion, and for intramuscular use where no vein is accessible; refrigerated, with a limited room-temperature period
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
PubChem CID 5314 — succinylcholine dication structure, formula and molecular weight; chloride salt CID 22475 (https://pubchem.ncbi.nlm.nih.gov/compound/5314) · a recorded source, not a stored snapshot
Incidence, culprit agent distribution and clinical features of perioperative anaphylaxis
✓ The study showed what it set out to show
Who was studied
NAP6 — 6th National Audit Project on perioperative anaphylaxis
How many people
266
Study design
National prospective audit of Grade 3 to 5 reactions over one year
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Estimated incidence about 1 in 10,000 anaesthetics; neuromuscular blocking agents 65 of 199 identified culprits; succinylcholine twofold more likely than other relaxants and mainly presenting with bronchospasm
Repeated elsewhere
Partially Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. True incidence might be about 70% higher after allowing for excluded and late reports; only 24% of cases reached the national pharmacovigilance scheme.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Sterile aqueous solution for intravenous injection and infusion, and for intramuscular use where no vein is accessible; refrigerated, with a limited room-temperature period
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
PubChem CID 5314 — succinylcholine dication structure, formula and molecular weight; chloride salt CID 22475 (https://pubchem.ncbi.nlm.nih.gov/compound/5314) · a recorded source, not a stored snapshot
Cardiac arrest and death from hyperkalaemic rhabdomyolysis in apparently healthy children with undiagnosed skeletal muscle myopathy
✓ The study showed what it set out to show
Who was studied
Post-marketing surveillance and case reports underlying the paediatric hyperkalaemic rhabdomyolysis boxed warning
How many people
0
Study design
Regulatory pharmacovigilance and published case reports
Compared against
Not recorded for this study
Kind of result
Living longer, or avoiding a major event
What was found
No trial exists and none could ethically be run. The evidence is case-based and the regulatory response was to restrict routine paediatric use rather than to quantify a rate.
Repeated elsewhere
Unreplicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The label does not state an incidence, and this page does not supply one. The affected population is by definition undiagnosed at the time of exposure, so a denominator is not available.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Sterile aqueous solution for intravenous injection and infusion, and for intramuscular use where no vein is accessible; refrigerated, with a limited room-temperature period
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
PubChem CID 5314 — succinylcholine dication structure, formula and molecular weight; chloride salt CID 22475 (https://pubchem.ncbi.nlm.nih.gov/compound/5314) · a recorded source, not a stored snapshot
What we know
RNAWiki holds 3 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Succinylcholine
What a person takes: Sterile aqueous solution for intravenous injection and infusion, and for intramuscular use where no vein is accessible; refrigerated, with a limited room-temperature period.
The measurement behind this step
Refrigeration is chemistry again: the molecule is a diester and hydrolyses in aqueous solution, so the potency of a warm vial falls with time. The intramuscular route exists specifically for the situation the boxed warning contemplates — a child with laryngospasm and no intravenous access — and it is the only common paralysing agent with a usable intramuscular route. There is no reversal agent and none is needed, because the plasma enzyme is the reversal mechanism.
Getting in
Injected, and most of it is destroyed on the way
An enzyme in the blood starts breaking the drug down the moment it is injected, so only a small fraction of the dose ever reaches the muscles.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Butyrylcholinesterase, also called plasma or pseudocholinesterase, hydrolyses succinylcholine in plasma to succinylmonocholine and then to succinic acid and choline. Because this happens before and during distribution, the amount arriving at the neuromuscular junction is a small fraction of the dose given, and the plasma enzyme rather than the receptor determines how long the block lasts.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
It reaches the endplate and switches the receptor on
Unlike every other paralysing agent, this one is not a blocker. It is a copy of the natural transmitter — two of them joined together — and it activates the receptor.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
The molecule is succinic acid diesterified with two cholines, structurally two acetylcholine molecules joined at their acyl ends. It binds the agonist sites at the alpha1-delta and alpha1-epsilon interfaces of the adult endplate receptor and opens the channel, producing the initial depolarisation seen clinically as fasciculation.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
The junctional enzyme cannot remove it, so the switch stays on
Acetylcholine is destroyed within a thousandth of a second so the muscle can reset. Succinylcholine is not, so the endplate stays permanently switched on and the muscle cannot fire again.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Acetylcholinesterase in the synaptic cleft hydrolyses acetylcholine within about a millisecond but does not act on succinylcholine. Persistent agonist occupancy holds the endplate depolarised; the voltage-gated sodium channels in the surrounding perijunctional membrane become inactivated and cannot regenerate an action potential, so the fibre is unexcitable despite being depolarised.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
Potassium leaves the muscle cell, which is usually trivial and sometimes fatal
Every time those channels open, potassium leaks out of the muscle into the blood. In a healthy person the rise is small. In someone whose muscle has grown extra receptors after a burn or a paralysis, it can be enough to stop the heart.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Serum potassium rises modestly in normal muscle. After denervation, burns, prolonged immobility or upper motor neuron injury, muscle expresses immature gamma-subunit-containing extrajunctional receptors across the whole fibre surface with prolonged channel open times, so agonist exposure produces a far larger and more widespread efflux. The label contraindicates use after the acute phase of such injuries and states that the onset and duration of the risk period are undetermined.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
Complete paralysis in about a minute, gone in about five
Onset is faster than anything else available, and recovery happens on its own without any antidote — because the enzyme in the blood has been working the whole time.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
The concentration gradient reverses as plasma drug is consumed, and succinylcholine diffuses back off the endplate into plasma to be hydrolysed. No reversal agent is used or needed, and an anticholinesterase given during a Phase I block prolongs it rather than reversing it, because inhibiting butyrylcholinesterase removes the only clearance mechanism there is.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
With prolonged exposure the block changes character
After enough drug or enough time, the block stops behaving like an overstimulated receptor and starts behaving like a blocked one — which changes what will and will not reverse it.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Phase I block shows no fade on train-of-four stimulation and no post-tetanic facilitation, and is deepened by anticholinesterases. With repeated or prolonged exposure it converts to a Phase II block that fades, shows post-tetanic facilitation and resembles a non-depolarising block, and may then respond to an anticholinesterase. The label warns that a Phase II block must be confirmed by a peripheral nerve stimulator and that spontaneous recovery must have plateaued, precisely because misdiagnosing the type and giving an anticholinesterase into a Phase I block prolongs the paralysis.
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 6 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Adults needing rapid intubation in an emergency department, an operating theatre or an ambulance, and patients having electroconvulsive therapy. Its paediatric use is now restricted by the label to emergencies.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On pediatric, the label states: “Safety and effectiveness of succinylcholine chloride have been established in pediatric patient age groups, neonate to adolescent.”
US prescribing information · f55dd1c0-c259-219a-5bca-f139e9515d07 · read 2026-08-30
On older people, the label states: “Clinical studies of succinylcholine chloride did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently from younger subjects.”
US prescribing information · f55dd1c0-c259-219a-5bca-f139e9515d07 · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary Available data from published literature from case reports and case series over decades of use with succinylcholine during pregnancy have not identified a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.”
US prescribing information · f55dd1c0-c259-219a-5bca-f139e9515d07 · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary There are no data on the presence of succinylcholine or its metabolite in either human or animal milk, the effects on the breastfed infant, or the effects on milk production.”
US prescribing information · f55dd1c0-c259-219a-5bca-f139e9515d07 · read 2026-08-30
Where the result stopped carrying
Routine paediatric use was withdrawn after apparently healthy children died of hyperkalaemic cardiac arrest, and the label now reserves paediatric use for emergency airway control
Seventy years of attempts to replace it have not produced a non-depolarising agent that matches it on intubating conditions in a pooled randomised comparison
Routine pharmacovigilance captured only 24% of the perioperative anaphylaxis cases a dedicated national audit found
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Given by a clinician
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Sterile aqueous solution for intravenous injection and infusion, and for intramuscular use where no vein is accessible; refrigerated, with a limited room-temperature period
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Suppression classes recorded: S6, S7.
No source is stored against this line.
What is in the pack
Refrigeration is chemistry again: the molecule is a diester and hydrolyses in aqueous solution, so the potency of a warm vial falls with time.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold. The rest of the recorded wording: The intramuscular route exists specifically for the situation the boxed warning contemplates — a child with laryngospasm and no intravenous access — and it is the only common paralysing agent with a usable intramuscular route. There is no reversal agent and none is needed, because the plasma enzyme is the reversal mechanism.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Carries a boxed warning for ventricular dysrhythmias, cardiac arrest and death from hyperkalaemic rhabdomyolysis in paediatric patients with undiagnosed skeletal muscle myopathy, most often Duchenne muscular dystrophy, and paediatric use is reserved for emergency airway control. Contraindicated in known or suspected malignant hyperthermia susceptibility, in skeletal muscle myopathies, in known hypersensitivity, and after the acute phase of major burns, multiple trauma, extensive denervation or upper motor neuron injury. Not recommended where plasma cholinesterase activity is reduced, whether genetically or from pregnancy, liver or kidney disease, tumours, infection, burns, anaemia, decompensated heart disease, peptic ulcer, myxoedema, or exposure to oral contraceptives, glucocorticoids, certain monoamine oxidase inhibitors or organophosphates. It paralyses without sedating. Myalgia after fasciculation is common. No dosing guidance appears on this page.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
Where this came from
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Sandoz Inc — boxed warning, contraindications, malignant hyperther… · a recorded source, not a stored snapshot
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Sterile aqueous solution for intravenous injection and infusion, and for intramuscular use where no vein is accessible; refrigerated, with a limited room-temperature period
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
A recorded note compares this form with the others that are sold. It is kept below, word for word.
§ A fixed RNAWiki sentence
Where this came from
Wording RNAWiki always uses, not a finding about this substance.
The recorded note, unchanged: The intramuscular route exists specifically for the situation the boxed warning contemplates — a child with laryngospasm and no intravenous access — and it is the only common paralysing agent with a usable intramuscular route. There is no reversal agent and none is needed, because the plasma enzyme is the reversal mechanism.
No source is stored against this line.
What is recorded as being sold
2 published labels name it as an active ingredient. 2 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · f55dd1c0-c259-219a-5bca-f139e9515d07 · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · f55dd1c0-c259-219a-5bca-f139e9515d07 · read 2026-08-29
Succinylcholine is intramuscular at 3 DOSAGE FORMS AND STRENGTHS Succinylcholine chloride injection, USP is supplied as a clear, colorless solution as follows: 200 mg/10 mL (20 mg/mL) in multiple-dose vials contains: 20 mg of succinylcholine anhydrous (eq…, recorded as fda label in effect 2024-02-25 in the United States.
US prescribing information · f55dd1c0-c259-219a-5bca-f139e9515d07 · read 2026-08-30
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
Self-experiment planning is not offered for a prescription or clinician-supervised medicine. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Succinylcholine studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That an intubating-conditions advantage measured in elective patients settles the choice against rocuronium, when the harms driving that choice are rarer than the trials could detect
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That a child who appears healthy has no myopathy — the assumption the boxed warning exists to break
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the absence of severe adverse outcomes across 50 trials is evidence of safety rather than a statement about sample size
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the risk window after a burn or denervating injury is known; the label states its onset and duration are undetermined
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
How much did people take in the studies?
The sources RNAWiki checked hold nothing for this field.
Why it matters. A result belongs to an amount. Without the amount the result floats free.
What would answer it
A stored source that records it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Succinylcholine are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
A boxed warning written after healthy-looking children arrested and died
In plain words
For decades this was the standard paralysing agent for children. Then apparently healthy children began having cardiac arrest within minutes of receiving it, and were found afterwards to have muscular dystrophy nobody knew about. Routine paediatric use was withdrawn.
What was measured
That a drug safe in a healthy child is safe in every child who appears healthy — an assumption that fails precisely where the underlying myopathy has not yet declared itself
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The approved United States label carries a boxed warning stating that acute rhabdomyolysis with hyperkalaemia followed by ventricular dysrhythmias, cardiac arrest and death has occurred after administration of succinylcholine to apparently healthy paediatric patients subsequently found to have undiagnosed skeletal muscle myopathy, most frequently Duchenne muscular dystrophy. It instructs that when a healthy-appearing paediatric patient arrests within minutes of administration, and this is not attributable to inadequate ventilation, oxygenation or anaesthetic overdose, immediate treatment for hyperkalaemia should be started, with concurrent treatment for malignant hyperthermia if its signs are present. It reserves paediatric use for emergency intubation or where immediate securing of the airway is necessary — laryngospasm, difficult airway, full stomach — or for intramuscular use where no vein is accessible. Duchenne muscular dystrophy is X-linked and typically undiagnosed in a boy under about four years old, so the children at risk were by definition the ones who looked well. This is a genuine reversal: a drug given to essentially every anaesthetised child became a drug reserved for emergencies, on the strength of a mechanism nobody had anticipated in a population nobody could identify in advance.
Source
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, BOXED WARNING and Warnings and Precautions 5.1 (DailyMed SPL 04a4e6f5-6fa1-42e1-a3f9-21fca7786b15)
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
Still the best drug for intubating conditions after seventy years of replacements
In plain words
Every randomised comparison against the modern alternative was pooled: fifty trials, four thousand one hundred and fifty-one patients. The 1952 drug still produced better conditions for getting a breathing tube in.
What was measured
Risk ratio for excellent and clinically acceptable intubating conditions across 50 randomised trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Tran and colleagues pooled 50 randomised and controlled clinical trials with 4,151 participants comparing succinylcholine at 1 mg/kg or more with rocuronium at 0.6 mg/kg or more for rapid sequence or modified rapid sequence intubation, in any age group or setting. Succinylcholine was superior for excellent intubating conditions, risk ratio 0.86 (95% CI 0.81 to 0.92, n=4,151), and for clinically acceptable conditions, risk ratio 0.97 (95% CI 0.95 to 0.99, n=3,992 across 48 trials). Superiority was greater when thiopental was the induction agent, risk ratio 0.81 (95% CI 0.73 to 0.88, n=2,302, 28 trials). At the highest rocuronium dose there was no statistical difference in conditions, and the reviewers still concluded succinylcholine was clinically superior because of its shorter duration of action. High detection bias and significant heterogeneity make this moderate-quality evidence, and the conclusion was unchanged from the two previous updates. Notably, no severe adverse outcomes were reported in any included trial — which means these trials measured the advantage and were structurally incapable of measuring the disadvantage.
Written into the record, not signed off as a reviewed claim
About 1 in 2,500 people cannot clear it, and the label gives the number
In plain words
The drug is destroyed by an enzyme in the blood. Roughly one person in two and a half thousand has inherited two copies of a variant enzyme that barely touches it, and stays paralysed for hours instead of minutes.
What was measured
Stated population frequency of homozygosity for the atypical plasma cholinesterase gene, with named genetic and acquired causes of reduced activity
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The label states that patients homozygous for the atypical plasma cholinesterase gene, about 1 in 2,500, are extremely sensitive to the neuromuscular blocking effect of succinylcholine. It further lists the acquired causes of reduced plasma cholinesterase activity — pregnancy, severe liver or kidney disease, malignant tumours, infections, burns, anaemia, decompensated heart disease, peptic ulcer and myxoedema — and the drugs that lower it, including chronic oral contraceptives, glucocorticoids, certain monoamine oxidase inhibitors, and irreversible inhibitors such as organophosphate insecticides, echothiophate and certain antineoplastics. The label does not recommend the drug in patients with reduced plasma cholinesterase activity. This audit is filed as measured because the frequency is a stated, labelled number with a defined genetic basis, and because the consequence is entirely benign if anticipated and entirely alarming if not: a patient who cannot be woken must simply be kept anaesthetised and ventilated until the enzyme finishes its work.
Source
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, Warnings and Precautions 5.9 — Risk of Prolonged Neuromuscular Block in Patients with Reduced Plasma Cholinesterase Activity
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
Contraindicated after burns and denervation, because the muscle grows new receptors
In plain words
After a major burn, a crush injury, a spinal cord injury or prolonged paralysis, muscle spreads immature receptors across its whole surface instead of keeping them at the nerve junction. Giving this drug then dumps potassium out of every muscle cell at once, and can stop the heart.
What was measured
Labelled contraindications by injury type, with the risk window explicitly stated as undetermined
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The label contraindicates succinylcholine after the acute phase of injury following major burns, multiple trauma, extensive denervation of skeletal muscle or upper motor neuron injury, because administration in those patients may result in severe hyperkalaemia and cardiac arrest. The mechanism is receptor upregulation: denervated or immobilised muscle expresses immature extrajunctional nicotinic receptors containing the gamma rather than the epsilon subunit across the whole fibre membrane, and those channels have a longer open time. A depolarising agonist therefore opens far more channels, for longer, over a far larger membrane area, and the potassium efflux is systemic rather than local. The label also names chronic abdominal infection, subarachnoid haemorrhage and conditions causing degeneration of central and peripheral nervous systems as increasing the risk, and states that the onset and duration of the risk period after such injuries are undetermined — which is an honest admission that nobody knows exactly when the window opens or closes.
Source
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, CONTRAINDICATIONS and Warnings and Precautions 5.4
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
It triggers malignant hyperthermia, and the genes are named on the label
In plain words
In people carrying certain inherited muscle-calcium variants, this drug can start a runaway metabolic crisis with rigidity, high temperature and muscle breakdown. It is a contraindication, and the risk rises when it is combined with an anaesthetic gas.
What was measured
Labelled contraindication with named susceptibility genes RYR1 and CACNA1S, and stated potentiation by concomitant volatile anaesthetic
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The label contraindicates succinylcholine in patients with known or suspected genetic susceptibility to malignant hyperthermia, and separately in skeletal muscle myopathies. Its warnings state that in susceptible individuals succinylcholine may trigger malignant hyperthermia, a skeletal muscle hypermetabolic state leading to high oxygen demand, that fatal outcomes have been reported, and that the risk increases with concomitant administration of a volatile anaesthetic. It names inherited ryanodine receptor RYR1 and dihydropyridine receptor CACNA1S variants as the genetic basis, and lists hyperthermia, hypoxia, hypercapnia and muscle rigidity including masseter spasm among the signs. Succinylcholine and the volatile agents are the two trigger classes in anaesthesia, and this drug is the only one of the two that can be avoided without abandoning general anaesthesia altogether.
Source
FDA-approved US prescribing information for ANECTINE (succinylcholine chloride) injection, CONTRAINDICATIONS and Warnings and Precautions 5.5 — Malignant Hyperthermia
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
Twice as likely to cause anaphylaxis as the other relaxants, usually as bronchospasm
In plain words
A year-long national audit of serious allergic reactions under anaesthesia found paralysing agents second only to antibiotics as a cause, and within that class succinylcholine was twice as likely as the others — typically presenting as sudden difficulty ventilating rather than as a rash.
What was measured
Relative frequency of succinylcholine-induced anaphylaxis against other neuromuscular blocking agents, and its characteristic presenting feature
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The 6th National Audit Project reviewed 266 reports of Grade 3 to 5 perioperative anaphylaxis over one year across all NHS hospitals, estimating an overall incidence of about 1 in 10,000 anaesthetics and noting that exclusions for reporting delay and incomplete data mean the true figure might be about 70% higher. Of 199 identified culprit agents, neuromuscular blocking agents accounted for 65, second to antibiotics at 94. Succinylcholine-induced anaphylaxis, mainly presenting with bronchospasm, was twofold more likely than with the other neuromuscular blocking agents, whereas atracurium-induced anaphylaxis mainly presented with hypotension and the non-depolarising agents had similar incidences to one another. Onset was rapid for relaxants. Across all agents there were 40 cardiac arrests and 10 deaths, with pulseless electrical activity the usual arrest rhythm, and poor outcomes associated with higher ASA grade, obesity and beta blocker or angiotensin-converting enzyme inhibitor use. Only 24% of cases had been reported through the national pharmacovigilance scheme.
Written into the record, not signed off as a reviewed claim
The advantage is measured in seconds; the harms are measured in case reports
In plain words
The trials that show this drug is better all measure the same thing: how good the view was when the tube went in. The reasons to avoid it are rare disasters that no trial of a few thousand elective patients could ever contain.
What was measured
That an intubating-conditions advantage established in 4,151 elective patients settles the choice, when the harms driving the alternative occur at frequencies those trials could not have observed
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Cochrane review is explicit that no severe adverse outcomes were reported in any of its 50 included trials. That is not evidence of safety; it is a statement about what a trial of 4,151 mostly elective patients can detect. Hyperkalaemic arrest in undiagnosed myopathy, malignant hyperthermia, and prolonged block from homozygous atypical cholinesterase all occur at frequencies between roughly 1 in 2,500 and considerably rarer, and the boxed warning was assembled from case reports and post-marketing surveillance rather than from a randomised comparison. This produces a structural asymmetry that a reader should see plainly: the benefit is quantified with confidence intervals, and the harms are quantified as labelled contraindications and population frequencies. Both are real. They are not commensurable, and any statement that succinylcholine is "better" or "worse" than rocuronium is a statement about how a clinician weighs a measured common advantage against an unmeasured rare catastrophe.
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What is not here
8 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
What was measured, goal by goal — found nothing in the sources checked.
How close this is to real life — found nothing in the sources checked.
Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
How this medicine reached us — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
Two acetylcholine molecules joined tail to tail, which paralyses by switching the endplate on rather than off and wears off in minutes because a plasma enzyme destroys it before most of it ever reaches the muscle — still superior to rocuronium for excellent intubating conditions across 50 trials and 4,151 patients (risk ratio 0.86), and carrying a boxed warning added after healthy-looking children with undiagnosed muscular dystrophy died of hyperkalaemic cardiac arrest.
Recorded evidence blocks (7)
Q2
On the Succinylcholine label: indicated for what?
"QUELICIN is indicated in adults and pediatric patients: • as an adjunct to general anesthesia • to facilitate tracheal intubation • to provide skeletal muscle relaxation during surgery or mechanical ventilation. QUELICIN is a depolarizing neuromuscular blocker indicated in adults and pediatric patients: • as an…": indications and usage on Succinylcholine's label. DailyMed label · fb08161e-7711-406d-e7b3-ea4515c07983 · 2026-08-18
Q3
30 registered trials of Succinylcholine — at which phases?
"recent publication (Ghezel-Ahmadi. Thorac Cardiovasc Surg. 2014 Nov 21)"; 1 of 30 registered studies
Show the evidence
TrialNCT01579864
terminated; "recent publication (Ghezel-Ahmadi. Thorac Cardiovasc Surg. 2014 Nov 21)"
recorded 2026-09-01 · last checked 2026-09-04
Q5
Which 11 trials of Succinylcholine posted no result?
Posted no result
11 of 11 completed trials
Registrations
NCT00004697, NCT00953550, NCT01127022, NCT01902641, NCT02237443 and NCT01571908, and 5 more
Completion dates
oldest 1999-03; newest 2024-03-17
Show the evidence
Trial
NCT00004697
1999-03
NCT00953550
2011-02
NCT01127022
2011-12
NCT01902641
2012-03
NCT02237443
2015-02
NCT01571908
2015-07
5 further recorded trials
NCT02667353
2015-12
NCT05556408
2015-12-30
NCT03312140
2017-02-08
NCT02822144
2020-08
NCT04868409
2024-03-17
Q6
At the median, Succinylcholine's trials enrolled 101 people — anything larger?
Median enrolment
101
Largest enrolment
30430
Registered trials counted
30
Q7
What do 470 spontaneous reports say about Succinylcholine — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Succinylcholine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 470 reaction mentions were counted: hyperthermia malignant 161; hypotension 64; anaphylactic shock 53; anaphylactic reaction 41. FAERS via Open Targets · CHEMBL703 · 2026-06-24
Show the evidence
hyperthermia malignant
161
hypotension
64
anaphylactic shock
53
anaphylactic reaction
41
premature baby
36
cardiac arrest
34
4 more recorded rows
bradycardia
21
tachycardia
21
rhabdomyolysis
20
bronchospasm
19
recorded 2026-06-24 · last checked 2026-09-04
Q8
Which 10 reactions does Succinylcholine's label not list?
ChEMBL 37 — CC BY-SA 3.0 Unported · ChEMBL ATC CC BY-SA · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 5 source rows
✓ no critical contamination: no quarantine open
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.