OVERDOSE
When the drug produces overstimulation, the clinical picture
is one of increasing parasympathomimetic action that is more or less
characteristic when not masked by the use of atropine.
Signs and symptoms of overdosage, including cholinergic
crises, vary considerably. They are usually manifested by increasing
gastrointestinal stimulation with epigastric distress, abdominal cramps,
diarrhea and vomiting, excessive salivation, pallor, pollakiuria, cold
sweating, urinary urgency, blurring of vision, and eventually fasciculation and
paralysis of voluntary muscles, including those of the tongue (thick tongue and
difficulty in swallowing), shoulder, neck, and arms. Rarely, generalized
malaise and vertigo may occur. Miosis, increase in blood pressure with or
without bradycardia, and finally, subjective sensations of internal trembling,
and often severe anxiety and panic may complete the picture. A cholinergic
crisis is usually differentiated from the weakness and paralysis of myasthenia
gravis insufficiently treated by cholinergic drugs by the fact that myasthenic
weakness is not accompanied by any of the above signs and symptoms, except the
last two subjective ones (anxiety and panic).
Since the warning of overdosage is minimal, the existence
of a narrow margin between the first appearance of side effects and serious
toxic effects must be borne in mind constantly. If signs of overdosage occur
(excessive gastrointestinal stimulation, excessive salivation, miosis, and more
serious fasciculations of voluntary muscles) discontinue temporarily all cholinergic
medication and administer from 0.5 mg to 1 mg (1/120 to 1/60 grain) of atropine
intravenously. In case of overdose, Pralidoxime Chloride may be used. Give other
supportive treatment as indicated (artificial respiration, tracheotomy, oxygen,
and hospitalization).
CONTRAINDICATIONS
Routine administration of atropine with MYTELASE (ambenoium chloride) is
contraindicated since belladonna derivatives may suppress the
parasympathomimetic (muscarinic) symptoms of excessive gastrointestinal
stimulation, leaving only the more serious symptoms of fasciculation and paralysis
of voluntary muscles as signs of overdosage.
MYTELASE (ambenoium chloride) should not be administered to patients receiving
mecamylamine, or any other ganglionic blocking agents. MYTELASE (ambenoium chloride) should also not
be administered to patients with a known hypersensitivity to ambenonium chloride
or any other ingredients of MYTELASE (ambenoium chloride) .