The original curare-derived muscle relaxant for surgery
Tubocurarine
An old curare-derived medicine used during surgery to relax and paralyse muscles, now largely replaced.
What is Tubocurarine?
Tubocurarine is the original muscle-relaxing medicine derived from curare, the plant extract once used on arrows. It is given during surgery and anaesthesia to relax or completely paralyse the muscles, making operations and the use of a breathing tube possible. Because it paralyses all muscles, including those used for breathing, it must only ever be used by an anaesthetist with full equipment to breathe for the patient. It can also cause the release of histamine, leading to a drop in blood pressure. It is now largely historical, having been replaced by newer, better-controlled muscle relaxants.
Education and reference only. This is a plain-language guide to Tubocurarine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Tubocurarine is a neuromuscular blocking agent, a type of medicine that relaxes and paralyses the body's voluntary muscles. It is the original such drug, purified from curare, the South American plant extract famously used as an arrow poison. In medicine it was given during surgery to keep muscles completely relaxed so that operations could be carried out and a breathing tube placed. It is given into a vein and only used as part of a general anaesthetic. Today it is largely of historical importance, having been superseded by newer muscle relaxants that are easier and safer to control.
How it works
Muscles contract when nerves release a chemical messenger called acetylcholine, which lands on receptors on the muscle. Tubocurarine blocks those receptors, so the messenger cannot get through and the muscle cannot contract, producing relaxation and, at full effect, paralysis. This is exactly what is needed for some surgery, but because it affects all voluntary muscles, including the diaphragm and other breathing muscles, it stops the person breathing on their own. That is why it is only ever given by an anaesthetist who is breathing for the patient with a ventilator. It can also prompt the body to release histamine, which can lower blood pressure.
Company & origin
Originated / developed by: Generic (historical).
The original curare-derived muscle relaxant, used during surgery to relax or paralyse muscles; now largely historical and superseded by newer agents.
Practical use
How to take Tubocurarine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given only by an anaesthetist, into a vein, as part of a general anaesthetic.
- It is used only where breathing can be fully taken over by a ventilator.
- It is always combined with medicines that provide sleep and pain relief, never given alone.
- Blood pressure and the heart are monitored closely, as it can cause a fall in blood pressure.
- Its effect is reversed or allowed to wear off under close supervision before normal breathing returns.
Weighing it up
Advantages & disadvantages of Tubocurarine
Advantages
- Provides the deep muscle relaxation needed for certain surgery and for placing a breathing tube.
- The original muscle relaxant, important in the history of safe anaesthesia.
- Largely replaced by newer agents that offer the same relaxation with better control.
Disadvantages
- Paralyses the breathing muscles, so the patient must be ventilated by machine.
- Can cause histamine release with a fall in blood pressure, flushing and wheezing.
- Largely historical, having been superseded by newer, more predictable relaxants.
Practical use
Good to know
The single most important point about tubocurarine is that it paralyses the muscles used for breathing, so a person given it cannot breathe by themselves and must have their breathing taken over by a machine. For this reason it is used only by anaesthetists in a fully equipped operating theatre or critical-care setting, never elsewhere. It also has an important side effect of causing the body to release histamine, which can lead to a fall in blood pressure, flushing and sometimes wheezing, so blood pressure is watched closely. It does not cause sleep or pain relief on its own, so it is always given together with anaesthetic and pain-relief medicines, otherwise a person could be paralysed yet still aware. It has largely been replaced by newer muscle relaxants that act more predictably and cause fewer of these problems.
Who should not take it / use with caution
- It must never be used outside a setting where breathing can be fully supported by a ventilator.
- People who have had a serious allergic reaction to it should not receive it.
- It is used with great caution in people prone to low blood pressure or with breathing or muscle conditions.
- It is given only by anaesthetists, never as a routine medicine.
Monitoring
- Continuous monitoring of breathing, which is taken over by a ventilator.
- Close monitoring of blood pressure and the heart.
- Checking the depth and recovery of muscle relaxation before breathing is left unsupported.
Side effects
- Complete paralysis of the muscles, including those used for breathing (the intended effect, requiring ventilation).
- A fall in blood pressure from histamine release.
- Flushing, wheezing or, rarely, severe allergic reactions.
- A slow recovery of muscle strength in some people, watched for before breathing is left unsupported.
Key interactions
- Some antibiotics and other medicines can deepen or prolong its paralysing effect.
- Certain anaesthetic gases and other muscle relaxants change how it works.
- It is balanced carefully against medicines that affect blood pressure and the heart.
Available as: A solution given into a vein during anaesthesia (historical).
Answers
Tubocurarine: frequently asked questions
What is tubocurarine used for?
It was used during surgery and anaesthesia to relax and paralyse the muscles, allowing operations to be carried out and a breathing tube to be placed.
Is it really related to curare?
Yes, it is the original muscle relaxant purified from curare, the South American plant extract once used as an arrow poison.
Why does it need an anaesthetist?
It paralyses the muscles used for breathing, so a person cannot breathe on their own and must have their breathing taken over by a machine under expert care.
Does it put you to sleep?
No, it only relaxes muscles; it does not cause sleep or pain relief, so it is always given with anaesthetic and pain-relief medicines.
Is it still used today?
It is largely historical and has been replaced by newer muscle relaxants that act more predictably and cause fewer side effects.
Authoritative sources
- BNF
- NICE CKS
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