What is another name for Decamethonium? A Look at Syncurine and C10

October 9, 2025 •

4 min read

First introduced in 1948, Decamethonium was a pioneering neuromuscular blocking agent for surgical anesthesia. It is most commonly known by its former brand name, Syncurine, and the shorthand C10. The drug was pivotal in the evolution of muscle relaxants but was ultimately replaced by safer, more controllable alternatives.

Quick Summary

Decamethonium, a historic depolarizing muscle relaxant, is also known by its brand names Syncurine, Eulissin, and Decacuran, and by its scientific shorthand, C10. It is now used almost exclusively for research purposes.

Key Points

Syncurine and C10: Decamethonium is also known by its former brand name, Syncurine, and the chemical shorthand, C10.
Depolarizing Blocker: It functions as a depolarizing neuromuscular blocker by binding to and persistently activating acetylcholine receptors, leading to paralysis.
Limited Clinical Use: Its use in surgical anesthesia was brief and occurred in the late 1940s and 1950s before it was replaced by more reliable drugs.
Irreversible Block: Unlike non-depolarizing agents, the Phase I block it produces cannot be effectively reversed by standard anticholinesterase medications.
Modern Research Tool: Today, it is primarily used in pharmacological research to study neuromuscular transmission and muscle physiology, not in clinical practice.
Other Brand Names: Less common brand names include Decacuran and Eulissin.

Other Names and Designations

While the chemical name is Decamethonium, it has been known by several other monikers throughout its history, particularly during its brief period of clinical use.

Syncurine: This was the brand name under which the British pharmaceutical company Burroughs Wellcome & Co. first marketed the drug in 1949.
C10: The compound is also frequently referred to by its chemical shorthand, C10, which refers to the ten-carbon chain linking the two quaternary ammonium groups.
Decacuran: Another former brand name for the medication.
Eulissin: Like Decacuran, this was another trade name for the drug.

The Role of Chemical Structure

The 'decamethylene' prefix in its name refers to the ten-carbon alkyl chain that connects the two charged quaternary nitrogen atoms. This specific distance between the charged groups was discovered to be optimal for binding to the nicotinic acetylcholine receptors at the neuromuscular junction, leading to its muscle-blocking effects.

Pharmacology and Mechanism of Action

Decamethonium is classified as a depolarizing neuromuscular blocking agent, which means it works in two distinct phases. Its mechanism is similar to that of the neurotransmitter acetylcholine, but its action is more prolonged because it is not broken down by the enzyme acetylcholinesterase.

Phase I Block (Depolarizing Phase):

Binding and Activation: Decamethonium binds to the nicotinic acetylcholine receptors (nAChR) on the motor endplate of skeletal muscle fibers.
Initial Stimulation: This binding mimics the action of acetylcholine, causing the motor endplate to depolarize and trigger transient muscle fasciculations (twitching).
Persistent Depolarization: Unlike acetylcholine, decamethonium is not rapidly hydrolyzed. This means the motor endplate remains persistently depolarized.
Paralysis: The prolonged depolarization inactivates voltage-gated sodium channels, preventing them from opening again. As a result, the muscle fibers become unresponsive to further nerve impulses, and flaccid paralysis ensues.

Phase II Block (Desensitizing Phase): If the drug concentration remains high or is administered for an extended period, the receptors can become desensitized and enter a state known as a Phase II block. This resembles the effect of a non-depolarizing blocker, where the endplate repolarizes but remains unresponsive to acetylcholine.

Historical Clinical Use and Decline

Decamethonium saw limited clinical use in anesthesia from the late 1940s to the 1950s, primarily to induce muscle relaxation during surgery and for electroconvulsive therapy. Despite its initial promise, several factors led to its rapid fall from favor.

Difficulty of Reversal: Unlike non-depolarizing agents, the effects of a Phase I block from decamethonium could not be reliably reversed by acetylcholinesterase inhibitors. This made the duration of paralysis less predictable and more challenging to manage.
Variable Patient Response: Clinical reports noted a wide variety of individual patient responses to the drug.
Side Effects: Concerns over prolonged paralysis, allergic reactions, and respiratory depression contributed to its limited and supervised use.

Its clinical use was largely supplanted by succinylcholine (suxamethonium), another depolarizing agent, and eventually by non-depolarizing agents with more predictable and reversible effects. Today, decamethonium is a historical compound primarily relegated to research to study neuromuscular transmission.

Comparison of Neuromuscular Blockers


Feature	Decamethonium (Syncurine)	Succinylcholine (Anectine)	Rocuronium (Zemuron)
Classification	Depolarizing neuromuscular blocker	Depolarizing neuromuscular blocker	Non-depolarizing neuromuscular blocker
Mechanism	Binds and activates nAChR, causing persistent depolarization.	Binds and activates nAChR, causing persistent depolarization.	Competitively blocks nAChR, preventing activation.
Clinical Use	Historical use in anesthesia; now for research.	Still used for rapid sequence intubation.	Widely used in modern anesthesia for muscle relaxation.
Onset Time	Slower onset compared to succinylcholine.	Very rapid onset (~30-60 seconds).	Rapid onset (1-2 minutes).
Duration	Relatively short duration of action, but unpredictable.	Very brief duration (~5-10 minutes).	Intermediate duration (30-40 minutes).
Reversibility	Cannot be reversed by anticholinesterase inhibitors in Phase I.	Effects wear off quickly due to plasma cholinesterase.	Reversible with anticholinesterase inhibitors (e.g., neostigmine) or sugammadex.
Distinctive Effect	Muscle fasciculations followed by paralysis.	Muscle fasciculations followed by paralysis.	No initial fasciculations.

Conclusion

Decamethonium, also known by trade names like Syncurine and Decacuran, and the chemical designation C10, represents an important, albeit brief, chapter in the history of anesthesia. As one of the first synthetic depolarizing neuromuscular blockers, it provided a valuable tool for muscle relaxation during surgery. However, its unreliability in reversal and notable side effects led to its replacement by more sophisticated agents like succinylcholine and non-depolarizing blockers. Its legacy persists in the form of C10, which continues to be a useful tool for pharmacological research into neuromuscular physiology and nerve transmission.

Key Research and Discovery

Paton and Zaimis (1949): The discovery of decamethonium’s potential for clinical use was based on research by Paton and Zaimis.
Early Clinical Trials (1949): Clinical reports on the use of decamethonium in anesthesia were published shortly after its discovery, marking a new era of muscle relaxation.
Emergence of Better Alternatives (1950s): The introduction of succinylcholine proved to be a superior option due to its more predictable and shorter duration, leading to decamethonium's clinical decline.
Contrasting Mechanisms: The different actions of decamethonium at the neuromuscular junction compared to ganglionic blockers like hexamethonium provided important insights into receptor types.
Contemporary Research Tool: In the decades since its clinical withdrawal, decamethonium has been used extensively as a research tool to study the mechanisms of muscle relaxation and receptor function.

Frequently Asked Questions

Another name for Decamethonium is its former brand name, Syncurine. It is also known by the chemical shorthand C10 and other historical brand names like Decacuran and Eulissin.

Decamethonium is a depolarizing neuromuscular blocking agent. Historically, it was used to induce temporary muscle paralysis during surgical procedures. Today, its use is almost exclusively confined to research settings.

Decamethonium's clinical use was discontinued due to several drawbacks, including the unpredictability of its effects, difficulty in reversing its block, and the development of newer, safer alternatives like succinylcholine and non-depolarizing blockers.

Decamethonium is a depolarizing agent, meaning it activates acetylcholine receptors before causing a block. This is different from non-depolarizing agents (like rocuronium), which act as competitive antagonists and prevent receptor activation from the outset.

While its use is limited today, side effects historically associated with Decamethonium include prolonged paralysis, allergic reactions, and potential respiratory depression due to its impact on muscle function.

Yes, Decamethonium and Succinylcholine are both classified as depolarizing neuromuscular blocking agents and have a similar mechanism of action. However, succinylcholine has a more rapid onset and shorter duration, making it a more useful and controllable agent for intubation.

C10 is a chemical shorthand for Decamethonium. It refers to the ten-carbon alkyl chain that connects the two quaternary ammonium groups in the drug's molecular structure.