Pyridostigmine bromide

How it works

It reversibly inhibits acetylcholinesterase at the neuromuscular junction, increasing acetylcholine availability and improving neuromuscular transmission.

Prescribing in practice

• Excessive dosing can precipitate a cholinergic crisis with weakness that mimics myasthenic worsening, so deterioration must be assessed carefully before increasing the dose.
• Cholinergic adverse effects include abdominal cramps, diarrhoea, salivation and bradycardia, and caution is needed in asthma, bradycardia and peptic ulcer disease.
• Use with caution and reduced exposure in renal impairment as it is largely renally excreted.

Monitoring

Monitor muscle strength and symptom control, heart rate and muscarinic side effects, distinguishing under- from over-treatment.

Counselling the patient

• Take doses on time, as timing relative to meals and activity can affect symptom control.
• Report increasing weakness, excessive salivation, cramps or diarrhoea.
• Seek urgent help if breathing or swallowing becomes difficult.

Evidence & guidelines

Pyridostigmine is an established first-line symptomatic treatment for myasthenia gravis.