Flextig

Indications

Neostigmine Methyl Sulphate injection is used in hospital to reverse the effects of certain muscle relaxants (non-depolarising neuromuscular blockers) at the end of surgery, so that normal breathing and muscle strength return. It is also used in myasthenia gravis (an autoimmune condition causing muscle weakness) when tablets cannot be taken, and sometimes to treat urine retention or a slow, non-moving bowel after surgery when there is no blockage.

How It Works

Nerves signal muscles using a chemical messenger called acetylcholine, which is broken down by the enzyme acetylcholinesterase. Neostigmine blocks this enzyme, so acetylcholine builds up at the junction between nerve and muscle. This helps overcome the muscle relaxant and strengthens muscle contraction. It also increases activity of the bowel and bladder.

Dosage and Administration

Neostigmine injection is given by a doctor or nurse, into a vein, muscle or under the skin, at a dose set for each patient. For reversal after surgery, it is given slowly into a vein together with, or just after, Atropine or Glycopyrronium, which protect against a slow heartbeat and excess secretions. Patients are monitored closely during and after the injection. Doses for myasthenia gravis and other uses are as prescribed by the specialist.

Interactions

• It can prolong the effect of depolarising muscle relaxants such as Suxamethonium.
• Aminoglycoside antibiotics (such as Gentamicin), Polymyxins, Clindamycin, Quinine and some anaesthetics can weaken its reversing effect.
• Beta-blockers (such as Propranolol) may increase the risk of a very slow heartbeat.
• Atropine and other anticholinergic medicines oppose its effects, which is why they are given together.
• Other cholinesterase inhibitors (such as Pyridostigmine or Donepezil) add to its effects.

Contraindications

• Allergy to Neostigmine or bromide/sulphate salts in the product.
• Mechanical blockage of the intestine or urinary tract.
• Peritonitis (infection of the lining of the abdomen) or doubtful bowel wall integrity.

Side Effects

Common effects come from extra acetylcholine activity: increased saliva, sweating, nausea, vomiting, stomach cramps, diarrhoea, frequent urination, watering eyes and small pupils. A slow heartbeat and low blood pressure can occur, especially if Atropine or Glycopyrronium is not given.

Less common but serious effects include tightening of the airways (bronchospasm), heart rhythm problems, fits and allergic reactions.

Patients are watched closely in hospital. Tell the nurse or doctor straight away if you feel faint, have wheezing or difficulty breathing, chest pain, severe stomach cramps, or increasing muscle weakness.

Pregnancy and Lactation

Neostigmine is used in pregnancy when the benefit outweighs the risk, for example in myasthenia gravis or after caesarean section; the doctor decides. Large doses given into a vein near term may affect the uterus. Very little is expected to pass into breast milk, and breastfeeding is usually possible; follow your doctor's advice.

Precautions and Warnings

Doctors use it carefully in people with asthma, heart disease, slow heartbeat, recent heart attack, low blood pressure, epilepsy, Parkinson's disease, peptic ulcer, an overactive thyroid, or kidney problems. Atropine should be available. Too much can cause a cholinergic crisis (worsening weakness), which can look similar to worsening myasthenia, so dosing must be supervised.

Overdose

Overdose causes a cholinergic crisis: heavy sweating, salivation, vomiting, diarrhoea, slow heartbeat, muscle twitching then weakness, and breathing difficulty. It is treated in hospital with Atropine, breathing support and other supportive care.

Therapeutic Class

Cholinesterase inhibitor (parasympathomimetic); reversal agent for non-depolarising neuromuscular blockade.

Storage

Hospital medicine: store as directed on the pack, usually below 30°C, protected from light. Do not freeze. Keep out of the reach of children.