pyridostigmine bromide: clinical use

Prescribing considerations

• Individualise treatment according to symptom pattern and functional response.
• Distinguish worsening myasthenia from cholinergic excess; both can cause increasing weakness but require different management.
• Renal impairment may increase exposure because renal elimination is important.
• Review requirements after thymectomy or when disease-modifying treatment is introduced.
• Ensure surgical and anaesthetic teams know that the patient takes pyridostigmine.

Contraindications and cautions

• Hypersensitivity to pyridostigmine, bromides or product excipients.
• Mechanical gastrointestinal obstruction.
• Mechanical urinary obstruction.
• Selected Mestinon tablets contain lactose and are unsuitable in specified rare hereditary disorders of sugar metabolism.
• Use particular caution with obstructive respiratory disease, bradycardia or conduction disorders, recent coronary occlusion, hypotension, peptic ulcer, epilepsy, Parkinsonism, hyperthyroidism and renal impairment.

Monitoring

• Assess muscle strength, swallowing, speech and respiratory symptoms.
• Monitor for cholinergic features such as diarrhoea, salivation, sweating, bronchial secretions, fasciculation and paradoxical weakness.
• Consider pulse, blood pressure and cardiac conduction in susceptible patients.
• Review renal function and treatment response where impairment is present.
• Reassess promptly if benefit shortens, adverse effects increase or weakness deteriorates.

Clinical pharmacology

Pyridostigmine is a quaternary ammonium reversible cholinesterase inhibitor. Oral absorption is incomplete and variable; it prolongs acetylcholine activity at synapses, has limited penetration of the blood–brain barrier and is substantially eliminated through the kidneys.

Formulation and product differences

• The selected product is an immediate-release oral tablet.
• The tablet is cross-scored and may be divided into halves or quarters.
• It contains lactose and must be protected from moisture and light in its original container.

Tablet

Route: Oral

Strengths: 60 mg