What is the equivalent oral dose of prednisolone (Omnacortil) when shifting from injectable methylprednisolone (MPS)?

Equivalent Oral Prednisolone (Omnacortil) Dose When Shifting from Injectable Methylprednisolone

When converting from injectable methylprednisolone (MPS) to oral prednisolone (Omnacortil), use a 1:1.25 conversion ratio - meaning 4 mg of injectable methylprednisolone is equivalent to 5 mg of oral prednisolone.

Conversion Principles

• The relative potency of methylprednisolone to prednisolone is 4:5, meaning methylprednisolone is slightly more potent than prednisolone 1
• When switching from intramuscular to oral administration, bioavailability must be considered, though studies show oral prednisolone has nearly complete bioavailability (approximately 100%) 2
• For patients previously receiving intramuscular methylprednisolone, the oral prednisolone dose should maintain equivalent anti-inflammatory and immunosuppressive effects 3

Specific Conversion Guidelines

• For patients receiving 120 mg intramuscular methylprednisolone, the equivalent oral prednisolone dose would be approximately 150 mg 3
• For maintenance therapy in rheumatologic conditions like polymyalgia rheumatica (PMR), oral prednisolone is typically started at 12.5-25 mg/day when converting from injectable therapy 3
• When tapering from high-dose injectable therapy, consider a gradual reduction in the oral prednisolone dose to minimize risk of disease flare 3

Clinical Considerations

• Consider patient-specific factors when determining exact conversion dose:

  • Disease severity and activity 3
  • Comorbidities that may increase risk of steroid-related side effects (diabetes, hypertension, osteoporosis, glaucoma) 3
  • Previous response to glucocorticoid therapy 3

• For patients with difficult-to-control comorbidities who were receiving intramuscular methylprednisolone specifically to reduce cumulative steroid exposure, consider starting at the lower end of the equivalent oral dose range 3

Dosing Schedule Considerations

• Single daily dosing of oral prednisolone is generally preferred over divided doses 3
• Split dosing may be considered only in special situations such as night pain while on low doses (<5 mg daily) 3
• For patients transitioning from weekly or biweekly intramuscular injections, calculate the weekly equivalent dose and divide appropriately for daily oral administration 1

Monitoring After Conversion

• Assess clinical response within 2-4 weeks of conversion to ensure adequate disease control 3
• Monitor for steroid-related adverse effects which may differ between administration routes 3
• If disease control is inadequate after conversion, consider increasing the oral prednisolone dose or adding steroid-sparing agents like methotrexate 3

Special Situations

• In multiple sclerosis, studies suggest that 1250 mg oral prednisolone provides similar bioavailability to 1000 mg IV methylprednisolone 4, 5
• For inflammatory conditions requiring pulse therapy, oral prednisolone can effectively replace IV methylprednisolone with appropriate dose adjustment 6, 5

Remember that the goal of conversion is to maintain disease control while minimizing glucocorticoid-related adverse effects through appropriate dosing and eventual tapering as clinically indicated 3.