anticholinesterases in the treatment of myasthenia gravis

Last reviewed 10/2022

Anticholinesterase compounds have traditionally been the mainstay of treatment for myasthenic patients e.g. pyridostigmine.

Common side effects include pupillary constriction, colic, diarrhoea, and increased salivation, sweating, lacrimation, and bronchial secretions. Adverse effects of these drugs - colic, diarrhoea - can usually be controlled by propantheline 15mg TDS (1).

The main problem inherent with symptomatic treatment is the ease with which the patient may pass from a myasthenic block and weakness sensitive to anticholinesterase, to a depolarisation block resultant from excessive acetylcholine at the motor end plate due to excess of the cholinesterase inhibitor.

In this scenario, further administration of the drug may be disastrous with possible respiratory paralysis. The resultant cholinergic crisis is managed by control of the airway and ventilation, administration of atropine and withdrawal of the drug. Immunosuppression or plasmapheresis may be required.

Spontaneous remissions may occur in 20% of patients treated with anticholinesterases alone.

Reference:

• (1) Prescribers' Journal 2000;40 (2): 93-98.
• (2) Jeffrey M. Statland, Emma Ciafaloni. Myasthenia gravis: Five new things Neurol Clin Pract. 2013 April; 3(2): 126-133.