Mestinon Warnings

Although failure of patients to show clinical improvement may reflect under dosage, it can also be indicative of overdose. As is true of all cholinergic drugs, overdosage of Mestinon may result in cholinergic crisis, a state characterized by increasing muscle weakness which, through involvement of the muscles of respiration, may lead to death. Myasthenic crisis due to an increase in the severity of the disease is also accompanied by extreme muscle weakness, and thus may be difficult to distinguish from cholinergic crisis on a symptomatic basis. Such differentiation is extremely important, since increases in doses of Mestinon or other drugs of this class in the presence of cholinergic crisis or of a refractory or "Insensitive" state could have a grave consequence. The different diagnosis of the two types of crisis may require the use of Tensilon (edrophonium chloride) as well as clinical judgment. The treatment of the two conditions obviously differs radically. Whereas the presence of myasthenia gravis suggests the need for more intensive anti-cholinergic therapy, the diagnosis of cholinergic crisis, calls for the prompt withdrawal of all drugs of this type. The immediate use of atropine in cholinergic crisis is also recommended.
Atropine may abolish or obtund gastrointestinal side effects or other muscarinic reactions: but such use, by masking the signs of overdose, can lead to inadvertent induction of cholinergic crisis.