Scoline

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Scoline

Method of action: Muscle Relaxant

Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Scoline

Quick Facts: Scoline

Property Description
Active Ingredient Suxamethonium Chloride (Succinylcholine)
Form Solution for Injection
Pharmacological Class Depolarizing Neuromuscular Blocker
Common Use Skeletal Muscle Relaxation
Origin Synthetic

What is the Classification and Origin of Scoline?

Scoline is the trade name for a synthetic medicine whose sole active ingredient is Suxamethonium Chloride, which is widely recognized internationally by its non-proprietary name Succinylcholine. It is formally classified as a Neuromuscular Blocker (NMBA), belonging specifically to the category of depolarizing neuromuscular blocking agents. This classification indicates the medicine temporarily halts communication between nerves and muscles.

This medicine is a choline derivative and a quaternary ammonium compound, confirming its synthetic origin and precise chemical structure. Scoline's status as a depolarizing agent is clinically recognized for providing a unique, rapid, and ultra-short-acting form of muscle relaxation necessary for acute interventions.


What is Scoline's Form and General Purpose?

Scoline is consistently supplied as a single active ingredient product formulated as a Sterile Nonpyrogenic Solution for Injection. This medicine is designed for parenteral delivery, typically via the intravenous route of administration, which is crucial for achieving the necessary rapid onset required in critical clinical settings.

The primary general purpose of Scoline is to produce complete, temporary skeletal muscle relaxation quickly. Succinylcholine is recognized as an essential medicine, a status that underscores its critical function in acute care and surgery. This allows physicians to perform crucial medical maneuvers that require absolute patient immobility, such as serving as an adjunct to general anesthesia or enabling the safe and precise placement of a breathing tube, known as tracheal intubation.

Regulatory References

  1. Suxamethonium (Succinylcholine) on WHO Essential Medicines List
  2. WHO Essential Medicines List entry

What side effects are possible with Scoline?

Possible Side Effects and Safety Information

Scoline (succinylcholine chloride) is a muscle relaxant that carries significant risks, which are detailed in regulatory warnings and contraindications.

Serious and Life-Threatening Reactions

The most critical risk is cardiac arrest resulting from acute rhabdomyolysis with hyperkalemia (high blood potassium), especially in pediatric patients with undiagnosed skeletal muscle myopathy. Fatal cases have been reported, leading regulatory bodies to advise reserving its use in children for emergency intubation. Scoline can also trigger malignant hyperthermia, a potentially fatal, acute onset condition characterized by high fever and muscle rigidity. Severe, life-threatening anaphylactic reactions (allergic reactions) have also been documented.

Contraindications and Safety Restrictions

Scoline is contraindicated (should not be used) in patients with a personal or familial history of malignant hyperthermia, known skeletal muscle myopathies, or a known hypersensitivity to the drug. It is also contraindicated after the acute phase of certain injuries, such as major burns, multiple trauma, or extensive denervation, due to the heightened risk of severe hyperkalemia.

Common Adverse Reactions

Commonly reported side effects include muscle fasciculations (twitching) upon injection, which can lead to postoperative muscle pain. Other effects include transient increases in intraocular, intracranial, and intragastric pressure, excessive salivation, and alterations in heart rhythm, such as bradycardia (slow heart rate), which is more frequent with repeated dosing, particularly in children.

Due to the paralysis it induces, the drug requires administration by professionals with access to immediate and full respiratory support.

Overdose and Emergency Response

Overdose and When to Seek Help

The official regulatory profile for Scoline defines overdose as a severe extension of its muscle-relaxing effect, primarily leading to prolonged respiratory muscle paralysis and apnea (complete cessation of breathing). This immediate and profound manifestation is the principal overdose presentation, necessitating instant, sustained respiratory support. An additional, distinct prolonged effect known as Phase II Block may occur following large or repeated overexposure.

Over-administration is associated with several serious, documented risks. A prominent warning addresses the potential for life-threatening outcomes, including cardiac arrest and death resulting from severe hyperkalemia and rhabdomyolysis. This critical risk is specifically documented for certain populations, such as pediatric patients with undiagnosed skeletal muscle myopathy. Scoline may also trigger Malignant Hyperthermia, a potentially fatal hypermetabolic crisis with signs like muscle rigidity, hyperthermia, and hemodynamic instability.

Urgent medical attention is required immediately upon suspicion of overdose, severe anaphylaxis, or the onset of prolonged apnea or signs of Malignant Hyperthermia. Regulators mandate that the drug be administered only where facilities for tracheal intubation and controlled respiration are instantly available. Official management is symptomatic and supportive, utilizing measures like mechanical ventilation and, for Malignant Hyperthermia, the administration of intravenous dantrolene sodium.

Therapeutic Uses of Scoline

Quick Facts About Scoline’s Uses

  • Indicated Use: May be used as an adjunct to general anesthesia.
  • Surgical Support: May help facilitate skeletal muscle relaxation during surgery.
  • Airway Management: May be used to facilitate tracheal intubation.
  • Ventilation: May help manage skeletal muscle relaxation during mechanical ventilation.

Scoline (succinylcholine chloride) is a therapeutic agent used primarily in controlled medical settings to facilitate procedures requiring temporary skeletal muscle relaxation. This medication is indicated as an adjunct to general anesthesia, meaning it is used in addition to other anesthetic agents to support the process.

Its key therapeutic uses include the facilitation of tracheal intubation, a procedure necessary for securing an airway. Additionally, it may be used to provide skeletal muscle relaxation during surgery or to support patients requiring mechanical ventilation. The medication is characterized by a rapid onset of effect and a short duration, which makes it an appropriate option for short medical and surgical procedures.

Eligibility and Restrictions for Use

Scoline (succinylcholine) is a prescription medicine used in adults and children as an adjunct to general anesthesia to facilitate tracheal intubation and provide skeletal muscle relaxation.

Populations for whom use is Contraindicated

This medicine must not be used in the following individuals due to the risk of severe, life-threatening hyperkalemia or malignant hyperthermia:

  • Persons with a personal or familial history of malignant hyperthermia.
  • Individuals with skeletal muscle myopathies (muscle disorders).
  • Patients with a known hypersensitivity (allergy) to succinylcholine.
  • Patients after the acute phase of injury following major burns, multiple trauma, extensive muscle denervation, or upper motor neuron injury.

Restricted or Cautionary Use

Population Eligibility Restriction
Pediatric Patients (Infants, Children, Adolescents) Use is restricted and must be reserved for emergency intubation or other situations where immediate securing of the airway is necessary, due to the risk of hyperkalemic rhabdomyolysis in those with undiagnosed myopathies.
Patients with certain conditions Use with great caution in those with pre-existing hyperkalemia, electrolyte abnormalities, severe liver disease, or conditions associated with reduced plasma cholinesterase activity, which may prolong the drug's effect.
Pregnancy/Lactation Plasma cholinesterase levels can decrease during pregnancy, potentially prolonging effects and requiring caution. Use during breastfeeding is not specifically documented as prohibited.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Official regulatory documents identify several medicinal agents that can significantly affect the action of Scoline (succinylcholine chloride), primarily by enhancing its neuromuscular blocking effect.

Documented Interacting Agents and Effects

Category of Interacting Agents Representative Examples (As Listed in Regulatory Labels) Interaction Outcome
Non-Penicillin Antibiotics Aminoglycosides (e.g., gentamicin, tobramycin), clindamycin, vancomycin, colistin Potentiate neuromuscular block
Antiarrhythmics / Local Anesthetics Quinidine, procainamide, lidocaine Enhance neuromuscular block
Anesthetics / Adjuncts Volatile anesthetics (e.g., isoflurane, desflurane), thiopental, non-depolarizing neuromuscular blockers Enhance or synergize effect
Other Agents Lithium carbonate, magnesium salts, oxytocin, metoclopramide, promazine, trimethaphan Enhance neuromuscular block

Clinical Considerations

The most prominent official concern is the enhancement of the neuromuscular blocking action, which requires careful monitoring during co-administration. Combining Scoline with other neuromuscular blocking agents during the same procedure requires consideration of a synergistic or antagonistic effect on the overall blockade. Additionally, the drug's effects on cardiac rhythm may be amplified by halogenated anesthetics, and the incidence of bradycardia is noted to be higher following a second dose.

Mechanism of Action

The mechanism of Scoline (Suxamethonium Chloride) is defined by a highly specific, rapid intervention at the neuromuscular junction, leading to flaccid paralysis. The drug acts as an agonist by binding directly to the Nicotinic Acetylcholine Receptor (nAChR) on the skeletal muscle motor end plate, functioning as a structural analog of Acetylcholine. This binding immediately opens the receptor's ion channel, forcing the muscle cell membrane into a state of persistent depolarization. This sustained electrical activation prevents the membrane from recovering its resting potential, rendering the muscle fiber refractory to any further motor commands. This unique mechanistic sequence, known as the depolarizing block, results in the failure of signal propagation essential for contraction, leading directly to flaccid paralysis across all skeletal muscles. Because this block is caused by persistent activation, the termination of the block relies solely on the drug's metabolism and removal from the receptor site.

Dosage and Administration Information

How to Use Scoline (Succinylcholine Chloride Injection)

Scoline (succinylcholine chloride) is a powerful medicine with strict administration guidelines and must only be used in a controlled medical setting. Its use is limited to administration by individuals skilled in managing artificial respiration, and equipment for tracheal intubation and ventilation must be instantly available. The following instructions summarize the use protocols for this medication.


Administration Scope

Administration Detail Requirement
Route of Administration Intravenous (IV) or Intramuscular (IM) use only.
Dosing Schedule Highly individualized based on patient assessment and body weight. The average IV dose for adults is 0.6 mg/kg. For continuous IV infusion, a diluted solution of 1 mg/mL to 2 mg/mL is administered.
Preparation Requirements The solution must be visually inspected for particulate matter or discoloration before use. Dilution is required for single-dose vials and for continuous infusion.
Age-Group Rules Specific, individualized doses are provided for pediatric patients (infants, older children, and adolescents) that differ from adult dosing.
Special Conditions Must not be administered until unconsciousness has been induced (except in emergencies). Neuromuscular function must be monitored during continuous infusion using a peripheral nerve stimulator.

Procedural Structure

The established guidelines involve a strict, multi-step protocol for using the drug. The initial steps require visual inspection of the solution and, if necessary, dilution to the required concentration for infusion. The subsequent step requires careful individualization of the dosage based on the patient's body weight and the type of procedure. Finally, the administration must be paired with continuous monitoring of the patient's neuromuscular status and full respiratory support facilities to maintain safe use.

Recent Clinical Evidence

Research Evidence / Overview of Studies


Overview of Pharmacodynamics

Scoline (suxamethonium chloride or succinylcholine) is a depolarizing neuromuscular blocking agent. Studies investigated its effect in relation to specific targets at the neuromuscular junction, which results in skeletal muscle paralysis. Research has also explored the timeframe within which initial measurable effects, such as muscle fasciculations followed by paralysis, were observed, often within the first minute of administration.


Efficacy and Combination Therapy Studies

Clinical trials have primarily evaluated Scoline's role in facilitating rapid procedures, such as tracheal intubation, and providing muscle relaxation during surgical procedures. Multiple comparative randomized controlled trials (RCTs) have compared the results of Scoline to other neuromuscular blockers, primarily focusing on intubation conditions and onset speed.

Meta-analyses aggregated data from several RCTs to evaluate whether Scoline, when compared to a non-depolarizing agent (rocuronium), was associated with differences in the frequency of excellent or unacceptable intubation conditions. These analyses generally suggest a higher proportion of excellent conditions with Scoline, along with a shorter duration for the intubation sequence.


Long-Term Safety and Tolerability

The long-term safety profile of the drug is generally assessed by evaluating the frequency of adverse events (AEs) across various clinical settings. Given its ultra-short duration of action (typically 5 to 10 minutes), long-term studies focus on short-term complications. The study findings detailed the frequency of specific adverse events, which may include transient effects like post-operative myalgia (muscle pain) and temporary increases in serum potassium levels. Data from extension studies or specific cohort evaluations did not typically include the identification of new safety signals beyond those commonly associated with the agent's depolarizing action.

Frequently Asked Questions (FAQ)

Common questions about Scoline (FAQ)

Q: Is Scoline the same type of medicine as a paralytic?

A: Scoline is classified as a depolarizing neuromuscular blocker, which is a type of medicine that causes a rapid and temporary flaccid paralysis (complete muscle relaxation) of the body's skeletal muscles. Official regulatory documents describe its main action as facilitating muscle relaxation.

Q: How quickly does Scoline start to work after it's given?

A: According to official product information, the onset of complete muscle paralysis after an intravenous injection is described as very rapid. This effect usually begins in less than one minute. This characteristic is relevant to its official use in critical clinical settings.

Q: How long do the effects of Scoline typically last?

A: Scoline is known as an ultra-short-acting agent. Following a single intravenous dose, the muscle-relaxing effects typically last for a short duration, approximately 4 to 6 minutes, before the muscles begin to recover.

Q: Is it normal to feel temporary muscle stiffness after Scoline wears off?

A: Official information mentions that a common side effect is postoperative muscle pain (myalgia). This may occur after the initial muscle twitching that happens when the medicine is first administered, which patients may experience as muscle stiffness or soreness.

Q: Is there a reversal medicine or antidote for Scoline?

A: Scoline's action is naturally terminated because it is very rapidly broken down in the bloodstream by an enzyme called plasma cholinesterase. While this natural breakdown is the primary way the effect wears off, in rare cases of prolonged paralysis, official information notes that anticholinesterase drugs (such as neostigmine) may be considered.

Q: Are there research studies looking at new ways to use Scoline?

A: Regulatory documents define the approved uses for Scoline as facilitating tracheal intubation and providing skeletal muscle relaxation during surgery or mechanical ventilation. These documents focus on the established, approved indications rather than potential new uses.

Q: What is the maximum number of times Scoline can be given in one procedure?

A: Regulatory labeling addresses administration by detailing that the drug can be given as a single initial dose, as repeated doses as needed, or as a continuous intravenous infusion for procedures that require longer muscle relaxation. Instead of setting a strict maximum number of injections, the official documents detail the administration methods for these dosing strategies.

Q: What do official documents say about the safety of Scoline during pregnancy?

A: Official information notes that plasma cholinesterase levels—the enzyme that breaks down Scoline—are naturally decreased during pregnancy, which may prolong the drug's effect. Use during pregnancy is categorized differently across agencies; for example, the US FDA assigns a Pregnancy Category C rating.

Q: Can a patient be awake or aware when Scoline is in effect?

A: Scoline is a muscle relaxant and has no effect on consciousness or the ability to feel pain. Regulatory warnings strictly state that it must only be administered when a patient is already under adequate general anesthesia or when unconsciousness has been medically induced.

Q: What does it mean if someone has an 'unusual' reaction to Scoline?

A: An 'unusual' reaction may refer to a prolonged neuromuscular blockade—meaning the paralysis lasts much longer than expected. Official documents note that this prolonged effect can occur in individuals who have atypical or deficient plasma cholinesterase, a condition that prevents the drug from being rapidly broken down.

Q: Is Scoline related to botox or nerve agents?

A: Scoline is chemically classified as a depolarizing neuromuscular blocker that acts on cholinergic receptors at the motor end plate. While not chemically related to botox or nerve agents, official labels do note that its effect may be enhanced when used with other muscle-affecting substances like botulinum toxin.

Q: Are there known food or drink interactions with Scoline?

A: Regulatory documents provide detailed information on potential interactions with various medicinal agents. However, these official labels typically do not list specific common food or drink items as interacting with Scoline.

Q: What is the main benefit of using Scoline over a non-depolarizing agent?

A: Research studies comparing Scoline to non-depolarizing agents indicate that Scoline is associated with a more rapid onset of action. This results in a shorter time needed for the intubation sequence and a higher rate of achieving excellent intubation conditions.

Q: How does the body break down and get rid of Scoline?

A: The body primarily breaks down Scoline by rapidly dissolving it in the blood plasma using the enzyme plasma cholinesterase. Once broken down, a small amount of the original drug and its metabolites are then excreted in the urine.

Q: Is Scoline ever used outside of operating rooms?

A: Regulatory documents indicate that facilitating tracheal intubation is a main use, which may be required in settings outside of a main operating room, such as emergency rooms and intensive care units.

Q: What should a patient know about their recovery period after receiving Scoline?

A: Since the effect wears off quickly, the full return of muscle function typically happens within minutes. The main temporary effects noted during recovery include the possibility of experiencing postoperative muscle pain (myalgia).

Q: Are there different forms or concentrations of Scoline available?

A: Official information confirms that Scoline is supplied as a sterile nonpyrogenic solution for injection in varying strengths. It is available in different concentrations, such as 20 mg/mL and 100 mg/mL.

Q: Is Scoline a controlled substance?

A: In the United States, Scoline (succinylcholine) is generally classified as a prescription-only medicine. It is not scheduled under the Controlled Substances Act (CSA) and is therefore not considered a controlled substance.

How should Scoline be stored and disposed of?

How to Store and Dispose of Scoline?

The official storage conditions for Scoline (Succinylcholine Chloride Injection) are strictly defined to maintain potency and safety.

Storage Requirements

  • Temperature: Store the unopened product under refrigeration between 2 C and 8 C (36 F and 46 F). The product must not be frozen.
  • Light Protection: The container should be kept in the original carton to protect the solution from light.
  • Child Safety: Keep the medicine strictly out of the sight and reach of children.

Handling and Disposal

  • Single-Use: As a single-dose product, any unused portion must be discarded immediately.
  • Disposal: The disposal of the expired or unused product, including the container, must be performed in accordance with local pharmaceutical waste regulations; do not dispose of it in household waste or wastewater.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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