Anesthetists use suxamethonium as a muscle relaxant. The drug is used during surgery and other medical procedures when relaxed muscles are necessary. These include intubation and bone repositioning. Side effects of the drug include extended paralysis, allergic reactions, and slow heartbeat. The drug usually only relaxes the muscles short term, but some patients may remain paralyzed for hours.
Suxamethonium is also known as succinylcholine. It comes in suxamethonium chloride, bromide, or iodide form. The major benefits of the drug for anesthetists are that it acts quickly, lasts only for a short time, and has a powerful, relaxing effect while in use.
There are two ways of administering the drug: injecting it directly into the vein or injecting it into the muscle. A typical adult dose of intravenous suxamethonium is one milligram per kilogram of body weight (mg/kg). An intramuscular dose can be up to three mg/kg.
To extend the relaxing effect, an anesthetist can top up the dose by injecting 0.3 mg/kg. In some cases, prolonged anesthesia is required, and the drug can be administered slowly through an intravenous drip. The patient must then be mechanically ventilated until the effects of the drug wear off.
Intravenous delivery acts more quickly than the intramuscular form and may take only thirty seconds to work. The drug temporarily prevents the muscles from contracting. After five or ten minutes, the paralytic effect usually wears off. Some people lack an enzyme that rapidly breaks down the drug, and these patients may stay in a paralytic state for hours.
Placing a tube down a patient's airway and inserting an endoscope to see inside the body is easier when the patient's muscles are relaxed. The drug is also useful to prevent muscle spasms in electroshock therapy. When an orthopedic doctor needs to reset bone, suxamethonium lowers the resistance to the bone repositioning.
Someone who has recently been burned, who has muscle injuries, or who has high potassium levels should not receive suxamethonium. For a certain time after the injury, paraplegic patients should also not be given the drug. The prolonged paralysis associated with the enzyme deficiency may also occur in people with diseases of the muscle.
During a procedure, suxamethonium can cause the heart rate to slow down. This happens more often in children than in adults and can be controlled by administering an atropine drug. After the surgery, muscle pains can occur, especially in patients who are mobile. Allergic reactions are also possible.