What is the equivalent intravenous (IV) dose of oral methylprednisolone?

Conversion of Oral Methylprednisolone to IV

When converting from oral methylprednisolone to intravenous (IV) methylprednisolone, use a 1:1 ratio—the doses are equivalent milligram-for-milligram because both formulations have similar bioavailability. 1, 2, 3

Direct Conversion Ratio

• Oral methylprednisolone and IV methylprednisolone are bioequivalent at the same dose, meaning 40 mg oral = 40 mg IV, and 80 mg oral = 80 mg IV 1, 2, 3
• The FDA label confirms that when given parenterally and in equimolar quantities, oral and IV methylprednisolone are equivalent in biologic activity 1
• Multiple randomized controlled trials have demonstrated non-inferiority of oral versus IV methylprednisolone at identical doses (1000 mg daily for 3 days), with no significant difference in clinical outcomes 2, 3

Clinical Context for Route Selection

Choose IV over oral methylprednisolone when:

• Rapid therapeutic effect is urgently needed for life-threatening conditions 4
• Patient cannot tolerate oral intake due to severe nausea, vomiting, or altered mental status 4
• High-dose pulse therapy (500-1000 mg daily) is required for severe autoimmune flares 5, 4
• Immediate peak concentrations are necessary for critical organ-threatening disease 4

Pharmacokinetic Considerations

• IV methylprednisolone produces demonstrable effects within one hour, with excretion nearly complete within 12 hours 1
• For constantly high blood levels, IV injections should be administered every 4-6 hours 1
• Oral methylprednisolone at high doses (≥500 mg) achieves similar area under the curve (AUC) as IV formulations, confirming equivalent total steroid absorption 6

Common Clinical Scenarios

For immune-related adverse events requiring escalation:

• If patient is on oral methylprednisolone and deteriorates, switch to IV methylprednisolone at the same or higher dose (typically 1-2 mg/kg/day IV for grade 3-4 toxicity) 5
• For immune-related myocarditis, initiate IV methylprednisolone 500-1000 mg daily for 3 days, then convert to oral prednisone (not methylprednisolone) at 1 mg/kg/day once troponin falls to <50% of peak 5

For severe autoimmune conditions:

• Pulse IV methylprednisolone 500-1000 mg daily for 1-3 days is standard for lupus nephritis, severe colitis, or pneumonitis 5, 4
• After pulse therapy completion, transition to oral prednisone (not back to oral methylprednisolone) at 0.5-1 mg/kg/day for maintenance 7, 4

Important Caveats

• Do not confuse methylprednisolone-to-prednisone conversion (1:1.25 ratio) with oral-to-IV methylprednisolone conversion (1:1 ratio) 7
• When converting from IV methylprednisolone to oral prednisone, use the 1:1.25 ratio: 40 mg IV methylprednisolone = 50 mg oral prednisone 7
• The oral route may cause more insomnia compared to IV administration at equivalent doses 2
• Both routes have similar safety profiles with comparable adverse event rates 2, 3