Suxalax

Indications

Suxamethonium Chloride (also called Succinylcholine) is a very short-acting muscle relaxant used during general anaesthesia. It relaxes the muscles quickly so that a breathing tube can be placed in the windpipe (intubation), and is also used for short procedures and to reduce muscle contractions during electroconvulsive therapy (ECT).

How It Works

It acts at the junction between nerves and muscles. It first causes brief muscle twitching, then keeps the muscle from responding to nerve signals, so the muscles become limp. The effect starts within about a minute and usually wears off within 5 to 10 minutes, as the drug is broken down by an enzyme in the blood called plasma cholinesterase.

Dosage and Administration

Suxamethonium is given only by an anaesthetist or trained doctor in an operating theatre or emergency setting, as an injection into a vein (rarely into a muscle). The dose depends on body weight and the procedure and is given as prescribed. Breathing is supported by machine or bag until the effect wears off.

Interactions

Its effect may be longer or stronger with medicines that lower cholinesterase activity, such as Neostigmine, some insecticides (organophosphates), Metoclopramide, certain antibiotics (Aminoglycosides, Polymyxins), Lithium, Magnesium and some anticancer drugs. Digoxin users may develop heart rhythm problems. The anaesthetist reviews all medicines before surgery.

Contraindications

Not used in people with a personal or family history of malignant hyperthermia, known allergy to the drug, high blood potassium, major burns, crush injuries or spinal cord injury after the first day or two, certain muscle diseases (such as muscular dystrophy), or known inherited low cholinesterase activity.

Side Effects

Muscle aches after surgery are common. Others include brief muscle twitching, a rise in blood potassium, slow or irregular heartbeat, increased pressure inside the eye, stomach and brain, increased saliva and, in some people, prolonged paralysis. Rarely, it can trigger malignant hyperthermia, a dangerous rise in body temperature with muscle rigidity, or a severe allergic reaction.

These effects are watched for and treated by the anaesthesia team. After the procedure, tell staff at once if you have severe muscle pain, dark urine, fever, palpitations or breathing difficulty.

Pregnancy and Lactation

It is used during caesarean section and is considered acceptable when needed; only small amounts cross the placenta. Cholinesterase levels are lower in pregnancy, so effects can last a little longer. Breastfeeding can usually continue once the mother is awake, as the drug is broken down very quickly.

Precautions and Warnings

Tell your doctor if you or a relative ever had problems with anaesthesia, prolonged paralysis or high fever during surgery, and about any muscle, nerve, kidney or eye disease (such as glaucoma) or recent serious injury or burns. It must be used only where full resuscitation equipment is available.

Overdose

Overdose causes prolonged muscle paralysis and inability to breathe. It is managed in hospital by continuing artificial breathing until the muscles recover; blood products containing cholinesterase may be used in some cases.

Therapeutic Class

Depolarising neuromuscular blocking agent (skeletal muscle relaxant used in anaesthesia).

Storage

Stored by the hospital as directed on the pack, usually in a refrigerator at 2 to 8°C, do not freeze, away from light and out of the reach of children.