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: 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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