What injectable corticosteroid is equivalent to oral prednisone?

Injectable Corticosteroid Equivalents to Oral Prednisone

Intramuscular methylprednisolone is the injectable corticosteroid equivalent to oral prednisone, with 120 mg given every 3 weeks being a common initial dosing regimen for conditions like polymyalgia rheumatica. 1, 2

Dose Equivalence and Conversion

• The FDA-approved methylprednisolone information indicates that 4 mg of methylprednisolone is equivalent to 5 mg of prednisone 3
• When converting from oral to injectable forms:
  • For short-term replacement: A single daily intramuscular injection equal to the total daily oral dose is usually sufficient
  • For prolonged effect: The weekly intramuscular dose can be calculated by multiplying the daily oral dose by 7 3

Clinical Application in Polymyalgia Rheumatica

Intramuscular methylprednisolone has been specifically studied as an alternative to oral prednisone in polymyalgia rheumatica with the following protocol:

• Initial dose: 120 mg every 3 weeks until week 9
• Week 12: Reduce to 100 mg
• Thereafter: Monthly injections with dose reduced by 20 mg every 12 weeks until week 48
• After week 48: Reduce dose by 20 mg every 16 weeks until discontinuation 1, 2

Advantages of Injectable Methylprednisolone

• Lower cumulative glucocorticoid dose (approximately 56% of the equivalent oral prednisone dose over long-term treatment) 4
• Significantly less weight gain compared to oral prednisone (0.82 kg vs 3.42 kg) 4
• Fewer fractures in long-term treatment (1 vs 8 in comparative studies) 4
• May be beneficial in patients with difficult-to-control comorbidities such as hypertension, diabetes, osteoporosis, and glaucoma 1, 2

Limitations and Considerations

• Not available in all countries 1
• Limited evidence for reduced side effects compared to oral therapy, except for weight gain 1
• The EULAR/ACR guidelines only conditionally recommend intramuscular methylprednisolone as an alternative to oral glucocorticoids 1, 2
• Efficacy supported by a single randomized controlled trial that was not designed as a non-inferiority trial 1

Administration Guidelines

• For maintenance therapy in rheumatoid arthritis: 40-120 mg intramuscularly at weekly intervals 3
• For dermatologic conditions: 40-120 mg intramuscularly at weekly intervals for 1-4 weeks 3
• For acute asthma or allergic rhinitis: 80-120 mg as a single dose 3

Important Cautions

• Avoid intrathecal administration of methylprednisolone acetate (Depo-Medrol) due to potential neurotoxicity from excipients like polyethylene glycol and miripirium chloride 5
• When choosing between oral and injectable forms, consider the patient's risk factors for glucocorticoid-related adverse events, particularly in females who may be more susceptible 1

For patients requiring long-term glucocorticoid therapy, intramuscular methylprednisolone offers a viable alternative to oral prednisone with potential benefits of reduced cumulative dose and fewer long-term side effects.