What are the proper administration instructions and common side effects of Pyridostigmine (Mestinon) for patients with myasthenia gravis?

Pyridostigmine Patient Education

How to Take Pyridostigmine

Start pyridostigmine at 30 mg orally three times daily and gradually increase based on your symptoms, up to a maximum of 120 mg four times daily as tolerated. 1, 2

Dosing Instructions

• Standard immediate-release tablets: Begin with 30 mg three times daily, taken at evenly spaced intervals throughout the day 1, 2
• Titration: Your neurologist will gradually increase your dose based on how well your symptoms improve and how well you tolerate the medication 1, 2
• Maximum dose: Do not exceed 120 mg four times daily (480 mg total per day) 1, 2
• Extended-release formulation: If prescribed the 180 mg extended-release tablets, take one to three tablets once or twice daily with at least 6 hours between doses 3
• Timing matters: Plan your daily activities around when you take your medication, as your muscle strength will be optimal 1-2 hours after each dose 2

Important Administration Tips

• Take the medication exactly as prescribed—do not skip doses or stop suddenly without consulting your neurologist 2
• Continue taking your morning dose on the day of any scheduled surgery or procedures unless specifically instructed otherwise by your physician 4
• The extended-release formulation may be combined with immediate-release tablets or syrup for better symptom control throughout the day 3

Common Side Effects

The most common side effects are gastrointestinal and include nausea, vomiting, diarrhea, abdominal cramps, flatulence, and increased salivation—these occur in up to 91% of patients taking pyridostigmine. 3, 5

Muscarinic Side Effects (Most Common)

• Gastrointestinal: Nausea, vomiting, diarrhea, abdominal cramps, increased bowel movements, flatulence 3, 5
• Urinary: Urinary urgency and frequency 5
• Respiratory: Increased bronchial secretions and saliva production 3
• Other: Excessive sweating (hyperhidrosis), small pupils (miosis), blurred vision 3, 5

Nicotinic Side Effects

• Muscle cramps, muscle twitching (fasciculations), and paradoxical muscle weakness 3, 5

Less Common Side Effects

• Skin rash (due to the bromide component)—this usually resolves when the medication is stopped 3

Managing Side Effects

• Most gastrointestinal side effects can be managed by taking the medication with food or adjusting the dose 5
• If side effects become intolerable, contact your neurologist before stopping the medication—approximately 26% of patients who discontinue pyridostigmine do so because of side effects, most commonly diarrhea, abdominal cramps, and muscle twitching 5
• Your doctor may prescribe atropine to counteract some muscarinic side effects, though this requires careful monitoring 3

Critical Medications to Avoid

You must strictly avoid certain medications that can worsen your myasthenia gravis symptoms and potentially trigger a life-threatening crisis. 1, 2

Antibiotics to Avoid

• Fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) 1, 2
• Aminoglycosides (gentamicin, tobramycin, amikacin) 1, 2
• Macrolides (azithromycin, clarithromycin, erythromycin) 1, 2

Other Medications to Avoid

• Beta-blockers (metoprolol, atenolol, propranolol) 1, 2
• Intravenous magnesium 1, 2
• Barbiturates (butalbital-containing medications like Fioricet) 2

What to Do

• Always inform every healthcare provider (including dentists, emergency room doctors, and pharmacists) that you have myasthenia gravis 2
• Check with your neurologist before starting any new medication, including over-the-counter drugs and supplements 2

Warning Signs Requiring Immediate Medical Attention

Seek emergency care immediately if you experience worsening difficulty breathing, swallowing problems, or rapidly progressive muscle weakness—these may indicate a myasthenic crisis. 2, 6

Symptoms to Monitor and Report

• Bulbar symptoms: Changes in speech (slurred or nasal quality), difficulty swallowing, facial weakness 2, 6
• Respiratory difficulties: Shortness of breath, inability to take deep breaths, feeling like you cannot get enough air 2, 6
• Visual changes: Double vision (diplopia), drooping eyelids that worsen throughout the day 2
• Generalized weakness: Significant increase in overall muscle weakness beyond your baseline 2

Crisis Management

• Myasthenic crisis requires hospitalization, often in an intensive care unit 2, 6
• Treatment may include IVIG (intravenous immunoglobulin) at 2 g/kg over 5 days or plasmapheresis 2, 6
• You will need frequent respiratory monitoring and may require temporary breathing support 6

Follow-Up and Monitoring

• Attend all scheduled neurology appointments to adjust your treatment as your symptoms change 2
• If you have more severe disease, your doctor may order regular pulmonary function tests to monitor your breathing strength 2, 6
• Keep a symptom diary to help your neurologist optimize your medication dosing 2