Is 10g of Intravenous Immunoglobulin (IVIG) over 5 days an appropriate treatment regimen for a 92kg patient with an acute exacerbation of myasthenia gravis?

Inappropriate IVIG Dosing for Myasthenia Gravis

The current regimen of 10g IVIG over 5 days is severely underdosed and clinically inappropriate for a 92kg patient with myasthenia gravis—the correct dose is 2 g/kg total (184g for this patient), administered as either 0.4 g/kg/day for 5 consecutive days (approximately 37g daily) or the full 2 g/kg divided over 5 days. 1, 2

Standard IVIG Dosing for Myasthenia Gravis

Acute Exacerbations and Crisis

• The established dose is 2 g/kg total over 5 days, which translates to 184g total for your 92kg patient 3, 1, 2
• This is typically administered as 0.4 g/kg/day for 5 consecutive days (approximately 37g daily for this patient) 2, 4
• IVIG at this dose is reserved for Grade 3-4 myasthenic exacerbations requiring hospitalization with ICU-level monitoring 1, 2

Current Dosing Error

• Your patient is receiving only 10g daily (50g total), which represents approximately 27% of the recommended total dose
• This underdosing is unlikely to produce the rapid clinical improvement expected from IVIG therapy, which typically begins at 6±2 days when properly dosed 4

Clinical Context for IVIG Use

When IVIG is Indicated

• Acute myasthenic crisis with respiratory compromise requiring hospitalization 1, 2
• Grade 3-4 toxicities with severe generalized weakness 3, 1
• Patients with respiratory insufficiency requiring frequent pulmonary function monitoring 3, 2
• As an alternative to plasmapheresis when plasma exchange is contraindicated or not feasible 5

When IVIG Should NOT Be Used

• Chronic maintenance therapy is explicitly not recommended by the American Academy of Neurology 1
• Mild to moderate symptoms (Grade 2 or less) that can be managed with pyridostigmine and corticosteroids 3, 1

Correct Management Algorithm

For Acute Crisis (Grade 3-4)

1. Admit to ICU for close respiratory monitoring 2
2. Administer IVIG 0.4 g/kg/day × 5 days (37g daily for 92kg patient) OR plasmapheresis for 5 days 3, 2
3. Continue corticosteroids (methylprednisolone 1-2 mg/kg daily or prednisone 1-1.5 mg/kg daily) 3, 2
4. Maintain pyridostigmine with dose adjustments based on response 2
5. Monitor pulmonary function frequently with negative inspiratory force and vital capacity 3, 2

For Moderate Symptoms (Grade 2)

1. Start or optimize pyridostigmine (30mg TID, titrate to max 120mg QID) 1, 6
2. Initiate corticosteroids (prednisone 1-1.5 mg/kg daily) if symptoms persist 3, 1
3. IVIG is not indicated at this severity level 3, 1

Critical Medication Avoidance

Ensure your patient avoids medications that worsen myasthenia: 3, 1, 6

• β-blockers
• IV magnesium
• Fluoroquinolone antibiotics
• Aminoglycoside antibiotics
• Macrolide antibiotics

Immediate Action Required

For your 92kg patient, you must either:

1. Increase the daily IVIG dose to 37g (0.4 g/kg) for the remaining days to approach therapeutic levels, OR
2. Reassess whether IVIG is truly indicated for this patient's clinical severity—if this is not a Grade 3-4 crisis, discontinue IVIG and optimize oral immunosuppression instead 1

The current 10g daily dosing represents a significant prescribing error that will likely result in treatment failure and unnecessary healthcare costs without clinical benefit.