Methylprednisolone to Prednisone Conversion
Use a 1:1.25 conversion ratio when switching from intravenous methylprednisolone (Solu-Medrol) to oral prednisone: 4 mg IV methylprednisolone equals 5 mg oral prednisone. 1, 2
Standard Conversion Framework
The conversion is based on relative glucocorticoid potency:
- Methylprednisolone is 5 times more potent than hydrocortisone 1, 2
- Prednisone is 4 times more potent than hydrocortisone 1, 2
- This yields the practical 4:5 ratio (methylprednisolone:prednisone) 1, 2
Common Conversion Examples
For typical clinical scenarios:
- 16 mg IV methylprednisolone = 20 mg oral prednisone 2
- 48 mg IV methylprednisolone = 60 mg oral prednisone 1
- 80 mg IV methylprednisolone = 100 mg oral prednisone (calculated from established ratio) 1, 2
Bioavailability Considerations
Oral methylprednisolone has approximately 69% bioavailability compared to IV administration, but this does NOT apply when converting to prednisone. 3 The conversion ratio already accounts for differences between the two drugs, so no additional adjustment for bioavailability is needed when switching from IV methylprednisolone to oral prednisone. 3
Prednisone itself has excellent oral bioavailability (84-95%) and is rapidly converted to active prednisolone. 4 This rapid conversion occurs within the first pass, making oral prednisone highly reliable for maintaining therapeutic effect. 4
Clinical Equivalence Evidence
Multiple studies confirm therapeutic equivalence when using proper conversion ratios:
- In hospitalized children with asthma, oral prednisone 2 mg/kg twice daily was equivalent to IV methylprednisolone 1 mg/kg four times daily (maintaining the 1:1.25 ratio when accounting for total daily dose) 5
- High-dose pulse therapy studies show no difference in clinical response between oral and IV routes when equivalent dosing is used 3
Practical Implementation
When converting, maintain the same dosing frequency initially:
- If patient was receiving methylprednisolone every 6 hours, start prednisone every 6 hours at the converted dose 2
- Once stable, consolidate to once-daily dosing as prednisone is typically given as a single morning dose 6
For high-dose pulse therapy (e.g., 500-2500 mg methylprednisolone):
- Transition to oral prednisone 0.3-0.5 mg/kg/day after pulse completion 6
- Taper to ≤7.5 mg/day by 3-6 months depending on indication 6
Critical Safety Points
Do not confuse methylprednisolone with methylprednisone—these are different compounds. 1 Always verify the exact medication name when calculating conversions.
The standard methylprednisolone dose pack (84 mg total over 6 days) is equivalent to only 105 mg prednisone and is often subtherapeutic for inflammatory conditions requiring 1 mg/kg/day dosing. 2 This common pitfall leads to inadequate treatment when clinicians assume the dose pack provides sufficient anti-inflammatory effect.