Mestinon 60mg (pyridostigmine)

Mestinon general information

What is Mestinon used for?

Mestinon tablets 60mg are used to treat myasthenia gravis, which literally means serious muscle weakness, and is a chronic neuromuscular disease of autoimmune origin (when the body produces antibodies against self) that is characterized by weakness and rapid fatigue of the muscles under voluntary control.  Muscles affected are those that control movements of the eye, eyelid, facial expressions, chewing, talking and swallowing.  In more serious cases, neck and limb muscles may become affected also muscles involved in breathing and this can lead to paralysis and the need for assisted breathing.  Symptoms include drooping of one or both eyelids (ptosis), blurred or double vision (diplopia), unstable or waddling gait, a change in facial expression, difficulty in swallowing, shortness of breath, impaired speech (dysarthria), and weakness in the arms, hands, fingers, legs, and neck.  The most common cause is due to autoantibodies that block the receptors for neurotransmitters (chemical messengers that allow nerve cells to communicate) and this causes break down in regulation of muscle control and increase in muscle weakness.  The thymus gland in adults with myasthenia gravis is often unusually large and they may also develop tumours of the thymus gland (thymoma) and this is thought to contribute to the dysfunctional immune system that leads to myasthenia gravis.  Mestinon tablets 60mg help restore normal function to the affected muscles to relieve symptoms of myasthenia gravis.  Mestinon tablets 60mg are also used to treat a severe form of constipation called paralytic ileus, in which the bowels become paralysed due to disruption of normal nerve and muscle function as a result of surgery, infection or medication like some pain medication and antidepressants.  Mestinon tablets 60mg are also used to treat postoperative urinary retention, in which the inability to pass following surgery can cause urine retention.

How does Mestinon work?

Mestinon tablets 60mg contain pyridostigmine bromide, a reversible cholinesterase antagonist that is used to treat myasthenia gravis, a condition where communication between nerve cells and muscle cells is deficient, which prevents muscles from contracting and results in muscle fatigue and weakness.  Normally a muscle contraction is stimulated by the neurotransmitter acetylcholine, a chemical messenger that allows nerve cells to communicate.  Acetylcholine travels across the junction between nerve and muscle cells, binding to a specific receptor on the surface of the muscle cell, which activates the cell and generates muscle contraction.  Antibodies produced against these receptors can block the nerve transmission and thereby block the signals for muscle contraction.  The enzyme cholinesterase normally breaks down acetylcholine once it has bound to its receptor and stimulated muscle contraction, to allow the muscle to relax and to allow for fresh signal transmission.  However, where the receptor in occupied by antibodies, there is insufficient acetylcholine to stimulate muscle contraction.  Pyridostigmine in Mestinon tablets 60mg blocks the action of acetylcholinesterase, which inhibits the breakdown of acetylcholine, allowing for muscle contraction to continue to be stimulated by the acetylcholine already bound to the remaining receptors.  This action has the effect of slowing down the breakdown of acetylcholine and potentiating the effect of naturally occurring acetylcholine.  Mestinon tablets 60mg help relieve symptoms of myasthenia gravis but cannot cure the disease.  Acetylcholine is also involved in gastrointestinal muscle contraction, which propels food along by peristalsis.  By inhibiting the breakdown of acetylcholine Pyridostigmine in Mestinon tablets 60mg helps overcome paralytic ileus by the same mechanism; also post-operative urinary retention.

What does Mestinon contain?

Mestinon tablets contain 60mg the active ingredient pyridostigmine (60mg) a reversible cholinesterase antagonist that is used to treat myasthenia gravis.  They also contain lactose, starch, precipitated silica, talc, magnesium stearate, purified water.

Treating myasthenia gravis with Mestinon

Mestinon tablets 60mg contain pyridostigmine, a reversible cholinesterase antagonist that is used to treat myasthenia gravis, a chronic automimmune neuromuscular disease (when the body produces antibodies against self).  This condition is characterized by weakness and rapid fatigue of the muscles under voluntary control because communication between nerve cells and muscle cells is deficient, which prevents muscles from contracting.  An unusually large thymus or tumour of the thymus gland (thymoma) is thought to contribute to the dysfunctional immune system that leads to myasthenia gravis.  Symptoms of myasthenia gravis include drooping of one or both eyelids (ptosis), blurred or double vision (diplopia), unstable or waddling gait, a change in facial expression, difficulty in swallowing, shortness of breath, impaired speech (dysarthria), and weakness in the arms, hands, fingers, legs, and neck.  If muscles involved in breathing become affected this can lead to paralysis and the need for assisted breathing.  Normally a muscle contraction is stimulated by the neurotransmitter acetylcholine, a chemical messenger that allows cells to communicate.  Acetylcholine travels across the junction between nerve and muscle cells, binding to a specific receptor on the surface of the muscle cell to, which activates the cell and generates muscle contraction.  Autoantibodies produced against these receptors can block the nerve transmission and thereby block the signals for muscle contraction.  The enzyme cholinesterase normally breaks down acetylcholine once it has bound to its receptor and stimulated muscle contraction, to allow the muscle to relax and to allow for fresh signal transmission.  However, where the receptor in occupied by antibodies, there is insufficient acetylcholine to stimulate muscle contraction.  Pyridostigmine in Mestinon tablets 60mg blocks the action of acetylcholinesterase, which inhibits acetylcholine breakdown allowing for muscle contraction to continue to be stimulated by the acetylcholine already bound to the remaining receptors.  This action has the effect of slowing down the breakdown of acetylcholine and potentiating the effect of naturally occurring acetylcholine.  Mestinon tablets 60mg help relieve symptoms of myasthenia gravis but cannot cure the disease. 

What are the side effects of Mestinon?

The most commonly reported side effects when taking Mestinon tablets 60mg include: nausea, vomiting, diarrhoea, abdominal cramps, increased salivation.

When should Mestinon not be used?

You should not use Mestinon tablets 60mg if you:

• are allergic to pyridostigmine or bomides or any ingredients in Mestinon
• are pregnant or are breastfeeding, without discussion with your doctor
• have kidney disease, without discussion with your doctor
• have obstructive respiratory diseases like bronchial asthma and chronic obstructive pulmonary disease (COPD)
• have any mechanical gastrointestinal or urinary obstruction
• have certain conditions including slow heart rate (bradycardia), recent coronary occlusion, low blood pressure (hypotension), vagotonia, (overactivity of the vagus nerve causes bradycardia, hypotension, constipation, sweating and painful muscle spasms), epilepsy or parkinsonism
• are taking medicines that interact with Mestinon, including other anticholinergic antimuscarinics like atropine and the antispasmodic hyoscine, depolarising muscle relaxants like suxamethonium, non-depolarising muscle relaxants like pancuronium and vecuronium, anaesthetics like cyclopropane or halothane, immunosuppressants, corticosteroids

What medications interact with Mestinon?

Several medications interact with Mestinon tablets 60mg and should either not be taken while you are taking Mestinon or only after discussion and instruction from your doctor:

• Drugs that cause a serious reaction with Mestinon:
• Drugs that affect Mestinon: other anticholinergic antimuscarinics like atropine and the antispasmodic hyoscine, immunosuppressants, corticosteroids
• Drugs that are affected by Mestinon: depolarising muscle relaxants like suxamethonium, non-depolarising muscle relaxants like pancuronium and vecuronium

How should Mestinon be taken?

You should take your Mestinon tablets 60mg swallowed whole with a glass of water.  The dose you take and how often depends on your condition and your doctor’s recommendation.  You will be advised to take your Mestinon tablets 60mg at intervals of 3-4 hours throughout the day, with higher doses as needed, such as first thing in the morning and before mealtimes, according to your doctor’s recommendation.  You should continue to take your Mestinon tablets 60mg for as long as recommended by your doctor.

How long should you take Mestinon?

You should continue to take your Mestinon tablets 60mg for as long as recommended by your doctor.

Missed dose of Mestinon

If you miss a dose of Mestinon tablets 60mg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Mestinon be stored?

You should store your Mestinon tablets 60mg below 25°C in a cool dry place and protected form light.