Pyridostigmine Bromide

Reference: ABPI Data Sheet Compendium, Page 1420/1421,Roche Products.


Presentation: Round white tablets with "Roche" imprinted across one face with two break bars across the other, containing 60 mg pyridostigmine bromide.


Properties: Mestinon is an antagonist to cholinesterase, the enzyme which normally destroys acetylcholine. The action of Mestinon can briefly be described, therefore, as the potentiation of naturally occurring acetylcholine. Mestinon has a more prolonged action than Prostigmin (neostigmine), although it is somewhat slower to take effect; because it has a weaker "muscarinic" action than Prostigmin, it is usually much better tolerated by myasthenic patients in whom the longer action is also an advantage.

Indications: Myesthinia Gravis, paralytic ileus; post operative urinary retention.

Dosage and administration: Mestinon has a gradual onset of effect (generally 30-60 minutes)

Myesthinia Gravis: Adults: Doses of 30 to 120 mg are given at intervals throughout the day when maximum strength is needed (for example, on rising and before mealtimes).

The usual duration of action of a dose is three to four hours in the daytime nut a longer effect (six hours) is often obtained with a dose taken on retiring for bed.

The total daily dose is usually 5-20 tablets but doses higher than these may be needed by some patients.

Newborn Infants: Neostigmine has generally been preferred in the treatment of neonatal myasthenia. However, Mestinon can be given, particularly if neostigmine proves unsuitable on account of pronounced cholinergic effects. The dosage requirements of Mestinon range from 5-10 mg every four hours, given 30--60 minutes before feeding.

Treatment is not usually required beyond eight weeks of age except in the rare conditions of congenital and familial infantile myasthenia.

Older children: Children under 6 years old should receive an initial dose of half a tablet (30 mg) of Mestinon; children 6-12 years should receive one tablet (60 mg). Dosage should be increased gradually as increments of 15-30 mg daily, until the maximum improvement is obtained. Total daily requirements are usually in the range of 30-360 mg.

The requirement for Mestinon is usually markedly decreased after thymectomy or when additional therapy (steroids, immunosuppressant drugs) is given.

When relatively large doses of Mestinon are taken by myasthenic patients it may be necessary to give atropine or other anticholinergic drugs to counteract the muscarinic effects. It should be noted that the slower gastrointestinal motility caused by these drugs may affect the absorbtion of aral Mestinon.

In all patients the possibility of "cholinergic crisis" due to overdose of mestinon, and its differentiation from "myasthenic crisis", due to increased severity of the disease, must be borne in mind. Both types of crisis are manifested by increased muscle weakness, but whereas myasthenic crisis may require more intensive anticholinesterase treatment, cholinergic crisis calls for immediate discontinuation of this treatment and institution of appropriate supportive measures, including respiratory assistance.

Other indications: Adults: the usual dose is 1-4 tablets

Children: 15-60 mg. The frequency of these doses may be varied according to the needs of the patient.

Elderly: There are no specific dosage recommendations for Mestinon in elderly patients.

Mestinon tablets are for oral administration.

Contra indications, warnings,etc.

Contra indications: Mestinon should not be given to patients with mechanical gastro intestinal or urinary obstruction.

Mestinon is contra indicated in patients with known hypersensitivity to the drug and bromides.

Mestinon should not be used in conjunction with depolarizing muscle relaxants such as suxamethonium as neuromuscular blockage may be potentiated and prolonged apnoea may result.

Use in pregnancy: The safety of Mestinon during pregnancy or lactation has not been established. Although the possible hazards to mother and child must be weighed against the potential benefits in every case, experience with Mestinon in pregnant patients with myasthenia gravis has revealed no untoward effects of the drug on the course of pregnancy.

As the severity of myasthenia gravis often fluctuates considerably, particular care is required to avoid cholinergic crisis, due to overdosage of the drug, but otherwise management is no different from that in non-pregnant patients.

Observations may indicate that only negligible amounts of Mestinon are excreted in breast milk, nevertheless, due regard should be paid to possible effects on the breast feeding infant.

Precautions: Extreme caution is required when administering Mestinon to patients with bronchial asthma.

Care should also be taken in patients with bradycardia, recent coronary occlusion, hypotension, vagotonia, epilepsy or Parkinsonism.

There is no evidence to suggest that Mestinon has any special effects in the elderly. However, elderly patients may be more susceptible to dysrhythmias than the younger adult.

Mestinon should not be given during cyclopropane or halothane anaesthesia, however it may be after withdrawal of these agents.

Side effects: These may include nausea and vomiting, increased salivation, diarrhoea and abdominal cramps.

Treatment of overdosage: Signs of overdosage due to muscarinic effects may include abdominal cramps, increased peristalsis, diarrhoea, nausea and vomiting, increased bronchial secretions, salivation, diaphoresis and miosis. Nicotinic effects consist of muscular cramps, fasciculations and general weakness. Bradycardia and hypotension may occur.

Artificial ventilation should be instituted if respiratory depression is severe. Atropine sulphate 1 to 2 mg intravenously is an antidote to the muscarinic effects.

Pharmaceutical precautions: Storage: Recommended maximum storage temperature for Mestinon tablets is 25 Degrees C, Mestinon tablets should be protected from light and moisture.



Package quantities: Mestinon tablets in packs of 200.

Product license No. 0031/5036R

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