Indications
Gallamine Triethiodide is a muscle relaxant used during general anaesthesia. It relaxes the body’s muscles so that a breathing tube can be placed in the windpipe and so that surgery, especially on the abdomen and chest, can be done more easily. It is an older medicine that has largely been replaced by newer muscle relaxants. It is a hospital-only medicine given by an anaesthetist.
How It Works
Nerves make muscles move by releasing a chemical messenger called acetylcholine at the junction between nerve and muscle. Gallamine blocks the receptors for acetylcholine on the muscle (a non-depolarising neuromuscular block), so the signal cannot pass and the muscles relax, including the breathing muscles. It also blocks the vagus nerve’s effect on the heart, which often speeds up the heart rate. It has no effect on consciousness or pain, so it is always given with anaesthetic and pain-relieving medicines.
Dosage and Administration
Given only by an anaesthetist, as an injection into a vein, after the patient is asleep. The dose is calculated from body weight and adjusted to the operation, as prescribed. Because the breathing muscles are relaxed, breathing is supported by a ventilator until the effect wears off or is reversed with medicines.
Interactions
- The effect is made stronger or longer by inhaled anaesthetics (such as Isoflurane or Sevoflurane), aminoglycoside antibiotics (such as Gentamicin or Streptomycin), Polymyxin, Clindamycin, Magnesium salts, Lithium, Quinidine, some calcium channel blockers and diuretics that lower potassium.
- Neostigmine reverses its effect at the end of surgery, usually given with Atropine or Glycopyrronium.
- Tell the anaesthetist about all medicines you take.
Contraindications
- Allergy to Gallamine or to iodide (iodine).
- Severe kidney failure, because the medicine is removed almost entirely by the kidneys and its effect can last much longer.
- Conditions in which a fast heart rate would be harmful, such as some heart diseases.
- Myasthenia gravis and other nerve-muscle diseases, unless the anaesthetist judges it necessary with great care.
Side Effects
Fast heart rate is common and blood pressure may rise slightly. If the effect is not fully reversed, weakness and difficulty breathing or swallowing can continue after surgery. Allergic reactions, including severe ones, can occur rarely.
These effects are watched for and treated by the theatre and recovery team. Tell staff at once, or get urgent medical help, if after anaesthesia you have trouble breathing, swallowing or speaking, marked muscle weakness, a racing heart, or swelling of the face or throat.
Pregnancy and Lactation
Gallamine crosses the placenta more than many other muscle relaxants, so it is generally avoided in pregnancy and during Caesarean section; the anaesthetist will choose the safest medicine. There is little information on breastfeeding; the anaesthetist will advise when to resume, usually once you have recovered from anaesthesia.
Precautions and Warnings
- Must only be given by staff trained in airway management, with ventilation equipment ready.
- Because it does not cause sleep, it must never be given without adequate anaesthesia.
- Effects are prolonged in kidney disease, low potassium, acidosis, low body temperature and nerve-muscle disorders.
- Burns and some muscle diseases change the response.
Overdose
Overdose causes long-lasting paralysis, including of breathing. It is managed in hospital with continued ventilation and reversal using Neostigmine with Atropine or Glycopyrronium until normal muscle strength returns.
Therapeutic Class
Non-depolarising neuromuscular blocking agent (skeletal muscle relaxant).
Storage
Hospital medicine: store as directed on the pack, below 30°C, protected from light. Do not freeze. Keep out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.