Celocurin (Suxamethonium Chloride)

What Is Celocurin and What Is It Used For?

Celocurin (suxamethonium chloride) is a depolarizing neuromuscular blocking agent that produces rapid, short-duration skeletal muscle relaxation. It is primarily used for emergency tracheal intubation, electroconvulsive therapy, and short surgical procedures where brief muscle paralysis is required.

Celocurin contains the active substance suxamethonium chloride, also known internationally as succinylcholine. It belongs to a group of medicines called peripherally acting muscle relaxants, specifically the subclass of depolarizing neuromuscular blocking agents. Unlike non-depolarizing agents such as rocuronium or vecuronium, suxamethonium works by mimicking the action of the neurotransmitter acetylcholine at the neuromuscular junction, causing an initial period of muscle depolarization followed by sustained relaxation.

Suxamethonium holds a unique position in clinical practice because it is the only depolarizing neuromuscular blocker currently in widespread clinical use. Despite the development of newer non-depolarizing agents, suxamethonium remains irreplaceable in certain clinical scenarios due to its unmatched rapid onset of action (30 to 60 seconds) and ultrashort duration (2 to 6 minutes). The World Health Organization includes suxamethonium on its Model List of Essential Medicines, recognizing it as one of the most important medications needed in a basic health system.

How Celocurin Works

Suxamethonium is a structural analogue of acetylcholine, the neurotransmitter responsible for transmitting nerve impulses to muscles. When injected intravenously, suxamethonium travels to the neuromuscular junction—the point where nerve fibers meet muscle fibers. Here, it binds to nicotinic acetylcholine receptors on the motor end plate of the muscle cell, mimicking the natural action of acetylcholine.

This binding causes an initial depolarization of the muscle membrane, which is clinically observed as brief, visible muscle twitching known as fasciculations. These fasciculations typically last a few seconds and indicate that the drug has reached the neuromuscular junction. Following this initial phase, the sustained presence of suxamethonium at the receptor causes a prolonged depolarization that renders the muscle unable to respond to further nerve stimulation, resulting in flaccid paralysis.

The duration of suxamethonium's effect is remarkably short because the drug is rapidly hydrolyzed (broken down) by an enzyme in the blood called plasma cholinesterase (also known as butyrylcholinesterase or pseudocholinesterase). This enzyme cleaves suxamethonium into succinylmonocholine and choline, and then further into succinic acid and choline—all inactive metabolites. The rapid enzymatic breakdown accounts for the ultrashort duration of action, typically 2 to 6 minutes after a single intravenous dose.

Clinical Uses

Celocurin is used in clinical situations where rapid-onset, short-duration muscle relaxation is required. Its primary indications include:

• Rapid-sequence tracheal intubation: The most common and critical use. When a tube must be inserted into the trachea quickly to secure the airway—particularly in emergency situations where the patient has a full stomach and is at risk of aspiration—suxamethonium provides the fastest and most reliable paralysis of the jaw and vocal cord muscles
• Electroconvulsive therapy (ECT): Used to attenuate the muscle contractions during therapeutic seizures, reducing the risk of fractures and injuries while allowing the beneficial effects of the electrical stimulation on the brain
• Repositioning of fractures and dislocations: Short-acting muscle relaxation facilitates the reduction of displaced bones or joints by relaxing the surrounding musculature, which may otherwise resist manipulation
• Diagnostic radiological examinations: Certain imaging procedures require the patient to remain completely still, and brief muscle relaxation can be used to facilitate optimal image quality
• Short surgical procedures: Any procedure requiring brief muscle relaxation where the ultrashort duration of suxamethonium is advantageous, avoiding the need for pharmacological reversal

What Should You Know Before Receiving Celocurin?

Celocurin must not be given to patients with a history of malignant hyperthermia, severe hyperkalemia, major burns or crush injuries, or known allergy to suxamethonium. Your anesthesiologist will assess your medical history, current medications, and family history of anesthetic reactions before administration.

Before receiving Celocurin, your anesthesiologist or critical care physician will conduct a thorough pre-operative assessment. This evaluation includes reviewing your complete medical history, current medications, family history of reactions to anesthesia, and blood chemistry results—particularly potassium levels. Because suxamethonium can cause significant physiological changes, understanding the contraindications and warnings is crucial for patient safety.

Contraindications

You must not receive Celocurin if you have any of the following conditions:

• Familial malignant hyperthermia: A personal or family history of this hereditary condition, which causes a life-threatening reaction to certain anesthetic agents including suxamethonium, is an absolute contraindication
• Severe hyperkalemia: If your blood potassium levels are already dangerously elevated, suxamethonium—which raises potassium further—could cause fatal cardiac arrhythmias
• Major burns: Patients with extensive burn injuries develop an upregulation of acetylcholine receptors across the muscle surface, which can lead to a massive release of potassium when suxamethonium is administered. This risk begins approximately 48 hours after the burn and can persist for months
• Major crush injuries or tissue trauma: Similar to burns, severe tissue damage can result in receptor changes that predispose to life-threatening hyperkalemia
• Kidney failure with elevated potassium: Impaired renal excretion of potassium combined with suxamethonium-induced potassium release can cause dangerous accumulation
• Severe prolonged sepsis: Chronic sepsis can cause muscle denervation-like changes that increase the risk of hyperkalemic response
• Known allergy to suxamethonium chloride: Hypersensitivity to the active substance or any of the excipients

Warnings and Precautions

Several important warnings apply to the use of Celocurin, and your healthcare team will carefully weigh the benefits against the risks:

Hyperkalemia: Administration of suxamethonium causes a transient rise in serum potassium levels of approximately 0.5 mmol/L in healthy patients. While this is usually clinically insignificant, it can cause serious or fatal consequences in susceptible individuals. Conditions that increase the risk of dangerous hyperkalemia include spinal cord injuries, prolonged bed rest or immobilization, neuromuscular diseases (such as muscular dystrophy), denervation injuries, and severe intra-abdominal infections. The hyperkalemia can manifest as slow heart rate (bradycardia), cardiac arrhythmias, low blood pressure, but also as elevated heart rate and high blood pressure.

Histamine release and anaphylaxis: Suxamethonium can trigger the release of histamine and other mediators, causing flushing, bronchospasm, hypotension, and in rare cases, full anaphylactic shock. Patients with a history of allergic reactions to other neuromuscular blocking agents may be at increased risk.

Cardiac effects: Suxamethonium can stimulate muscarinic receptors in the heart, leading to bradycardia (slow heart rate), especially with repeated doses or in children. In rare cases, cardiac rhythm disturbances can progress to cardiac arrest. Pre-treatment with atropine may be considered to reduce this risk.

Rhabdomyolysis: Severe muscle breakdown (rhabdomyolysis) with acute kidney failure and dark reddish-brown urine (caused by myoglobin) has been reported, particularly in patients with undiagnosed muscle disorders. This is a medical emergency requiring immediate treatment.

Pregnancy and Breastfeeding

If you are pregnant, planning to become pregnant, or breastfeeding, inform your healthcare team before receiving Celocurin.

Pregnancy: Suxamethonium may be broken down more slowly during pregnancy due to reduced plasma cholinesterase activity. Under normal circumstances, suxamethonium does not cross the placenta in significant amounts to affect the fetus. However, in rare cases where the fetus carries a genetic variant causing pseudocholinesterase deficiency, there is a theoretical risk of neonatal respiratory depression. Celocurin should therefore be used with caution during labor and delivery.

Breastfeeding: It is not known whether suxamethonium passes into breast milk. Given the ultrashort duration of action and rapid metabolism, significant exposure to a breastfed infant is considered unlikely. Consult your doctor for individual advice.

Driving and Operating Machinery

No formal studies on driving ability have been conducted. However, Celocurin is administered exclusively in hospital or clinical settings during procedures that themselves preclude driving. You should not drive or operate machinery until you have fully recovered from the procedure during which Celocurin was administered. Your healthcare team will advise you when it is safe to resume these activities.

Sodium Content

This medicine contains less than 1 mmol (23 mg) sodium per ampoule/vial, meaning it is essentially sodium-free.

How Does Celocurin Interact with Other Drugs?

Celocurin interacts with a number of medications that can either prolong or enhance its neuromuscular blocking effect. Plasma cholinesterase inhibitors, certain antibiotics, cancer drugs, and anesthetic agents can all significantly alter how long and how intensely Celocurin works. Always inform your anesthesiologist about all medications you are taking.

Drug interactions with suxamethonium are clinically significant because they can lead to prolonged paralysis and respiratory failure if not anticipated and managed. The interactions primarily involve drugs that either inhibit the enzyme responsible for breaking down suxamethonium (plasma cholinesterase) or that have their own effects on the neuromuscular junction. Your anesthesiologist will review all your current medications as part of the pre-operative assessment.

Major Interactions

The following medications can significantly enhance and/or prolong the neuromuscular blocking effect of Celocurin, potentially requiring dose adjustments or alternative agents:

Other Interactions

The following medications may also affect the neuromuscular blocking action of Celocurin, though typically to a lesser degree. Your anesthesiologist should still be aware of their use:

What Is the Correct Dosage of Celocurin?

Celocurin dosage is individualized based on the patient's weight, age, clinical condition, and the procedure being performed. For adults, the typical intravenous dose for intubation is 1 to 1.5 mg/kg body weight. The drug should only be dosed by an anesthesiologist, and the dose is carefully titrated to the individual patient.

Celocurin is exclusively administered by physicians specifically trained in anesthesia techniques. The dosage is individualized for each patient based on their body weight, age, physical condition, the degree and duration of muscle relaxation required, and the route of administration. The anesthesiologist determines the appropriate dose in real time, adjusting as needed based on the clinical response.

Route of Administration

Celocurin is given as an intravenous injection (into a vein) or intravenous infusion. In special situations where intravenous access is not available—particularly in emergency pediatric scenarios such as laryngospasm—it can be administered as an intramuscular injection (into a muscle) or, rarely, as an intraosseous injection (into the bone marrow cavity).

Adults

Children

Elderly

Overdose

Overdose with Celocurin is unlikely under normal clinical circumstances because dosing is carefully controlled and the patient is continuously monitored by the anesthesiologist. However, if an excessive dose is accidentally administered, the primary consequence is prolonged respiratory paralysis (apnea). In this event, the anesthesiologist will immediately maintain artificial ventilation and oxygen delivery until spontaneous breathing returns. There is no specific antidote for suxamethonium; management is entirely supportive.

Patients with pseudocholinesterase deficiency—a genetic condition affecting the enzyme that breaks down suxamethonium—are particularly vulnerable to prolonged paralysis. In these individuals, even standard doses can produce muscle relaxation lasting 30 minutes to several hours rather than the expected 5 to 10 minutes. Plasma cholinesterase activity can be measured by blood testing, and fresh frozen plasma may be administered to provide exogenous cholinesterase in severe cases.

What Are the Side Effects of Celocurin?

Like all medicines, Celocurin can cause side effects. The most common side effect is post-operative muscle pain (myalgia), occurring in more than 1 in 10 patients. Serious but rare side effects include malignant hyperthermia, cardiac arrest, and severe anaphylactic reactions. Most side effects are transient and manageable in the hospital setting.

Side effects of suxamethonium range from very common and relatively benign (such as muscle soreness) to rare but potentially life-threatening (such as malignant hyperthermia and cardiac arrest). Because Celocurin is always administered in a controlled clinical environment with continuous monitoring, most adverse effects can be detected and treated promptly. Understanding the frequency and nature of these effects helps healthcare teams prepare appropriate monitoring and interventions.

Post-Operative Muscle Pain

The most commonly reported side effect of suxamethonium is post-operative muscle pain, which can affect up to 50–90% of ambulatory patients according to some studies. The pain is thought to be caused by the initial fasciculations (involuntary muscle contractions) that occur immediately after injection. The severity of myalgia is generally greater in young, muscularly active patients and those undergoing minor ambulatory surgery where early mobilization is expected.

Various strategies have been studied to reduce suxamethonium-induced myalgia, including pre-treatment with small doses of non-depolarizing muscle relaxants (such as a “defasciculating” dose), non-steroidal anti-inflammatory drugs, or lidocaine. The effectiveness of these approaches varies, and your anesthesiologist will decide on the most appropriate strategy based on your individual circumstances.

Malignant Hyperthermia

Malignant hyperthermia (MH) is a rare but potentially fatal pharmacogenetic disorder triggered by suxamethonium and volatile anesthetic agents (such as halothane, sevoflurane, and desflurane). In genetically susceptible individuals—most commonly those with mutations in the ryanodine receptor gene (RYR1)—suxamethonium triggers uncontrolled calcium release from the sarcoplasmic reticulum of skeletal muscle cells.

Signs of malignant hyperthermia include rapidly increasing body temperature (often above 40°C), severe muscle rigidity (particularly jaw rigidity or “masseter spasm”), tachycardia, metabolic acidosis, hyperkalemia, and dark-colored urine. Treatment involves immediate discontinuation of all triggering agents and administration of dantrolene sodium, which inhibits calcium release from the sarcoplasmic reticulum. All facilities administering suxamethonium are required to have dantrolene immediately available.

How Should Celocurin Be Stored?

Celocurin should be stored in a refrigerator at 2 to 8 degrees Celsius. It may be stored at room temperature for up to 2 months when kept in emergency kits. Do not use after the expiry date on the packaging.

Proper storage of Celocurin is essential to maintain its efficacy and safety. Suxamethonium is a relatively unstable molecule that degrades more rapidly at higher temperatures, so cold-chain storage is the default requirement. The following storage guidelines apply:

• Refrigerated storage: Store at 2°C to 8°C (standard refrigerator temperature). This is the primary storage condition and maximizes the shelf life of the product
• Emergency kit storage: Celocurin may be stored in emergency bags and on-call kits at room temperature for up to 2 months. This practical exception recognizes the need for immediate availability in emergency situations
• Expiry date: Do not use after the expiry date printed on the carton and label (after “EXP”). The expiry date refers to the last day of the stated month
• Keep out of reach of children: Store in a location that is not accessible to children
• Disposal: Do not dispose of unused medicine via drains or household waste. Return unused or expired medicines to a pharmacy or healthcare facility for proper disposal in accordance with local regulations. This helps protect the environment

In clinical practice, the storage and handling of Celocurin are managed by hospital pharmacy departments and anesthesia teams. Patients do not typically handle or store this medication themselves, as it is exclusively administered in controlled healthcare settings.

What Does Celocurin Contain?

Each milliliter of Celocurin solution contains 50 mg of suxamethonium chloride as the active substance. The inactive ingredients include succinic acid, sodium hydroxide, and water for injections. The solution is clear and colorless.

Active Substance

The active substance is suxamethonium chloride (international non-proprietary name: suxamethonium; known in North America as succinylcholine). Each milliliter of the 50 mg/ml formulation contains 50 mg of suxamethonium chloride. Suxamethonium is chemically a dicholine ester of succinic acid, which explains its structural similarity to acetylcholine (a monocholine ester of acetic acid).

Inactive Ingredients (Excipients)

• Succinic acid: Used as a pH buffer to maintain the stability and acidity of the solution
• Sodium hydroxide: Used for pH adjustment
• Water for injections: The solvent for the solution

Appearance and Packaging

Celocurin is a clear, colorless solution. It is available in the following packaging configurations:

• Ampoules: 10 × 2 ml (50 mg/ml)
• Injection vials: 10 × 10 ml (50 mg/ml)
• Injection vial: 1 × 10 ml (50 mg/ml)
• Pre-filled syringes: 10 mg/ml solution

Not all pack sizes may be marketed in all countries. The pre-filled syringe formulation at 10 mg/ml concentration is designed for settings where a lower concentration provides more precise dosing, particularly in pediatric practice or when using infusion techniques.

Frequently Asked Questions About Celocurin

References

Editorial Team