Methylprednisolone to Prednisone Conversion
When converting from oral methylprednisolone to prednisone, use a ratio of 1:1.25, meaning 4 mg of methylprednisolone is equivalent to 5 mg of prednisone. 1
Detailed Conversion Guidelines
The conversion between these two commonly used corticosteroids follows a standard potency ratio:
- Methylprednisolone has 1.25× the potency of prednisone
- Therefore, to convert:
- Multiply methylprednisolone dose by 1.25 to get the equivalent prednisone dose
- Or divide prednisone dose by 1.25 to get the equivalent methylprednisolone dose
Practical Examples:
- 4 mg methylprednisolone = 5 mg prednisone
- 8 mg methylprednisolone = 10 mg prednisone
- 16 mg methylprednisolone = 20 mg prednisone
- 20 mg methylprednisolone = 25 mg prednisone
- 40 mg methylprednisolone = 50 mg prednisone
Pharmacological Considerations
Methylprednisolone and prednisone differ in several important ways that may influence clinical decision-making:
Mineralocorticoid Effects: Methylprednisolone has less mineralocorticoid activity than prednisone at equivalent doses, potentially causing less fluid retention and hypokalemia 1
Pharmacokinetics: Methylprednisolone shows linear pharmacokinetics with no apparent dose or time dependency, making its effects more predictable than prednisone, which demonstrates dose-dependent pharmacokinetics 2
Drug Interactions: Be aware that certain medications can affect steroid metabolism. For example, clarithromycin can reduce methylprednisolone clearance by 65% without significantly affecting prednisone clearance 3
Clinical Implications
When switching between these medications:
- Maintain the appropriate equivalent dose to ensure continued therapeutic effect
- Consider the timing of administration (morning dosing is generally preferred to align with natural cortisol rhythms) 4, 5
- Be aware that despite bioequivalent dosing, individual patient responses may vary
- Monitor for changes in clinical response or side effects after switching medications
Special Situations
For specific conditions like polymyalgia rheumatica, the recommended dose range is 12.5-25 mg prednisone equivalent daily 6, which would convert to 10-20 mg of methylprednisolone.
Caution Points
- Avoid abrupt discontinuation of either medication to prevent adrenal insufficiency
- Consider tapering schedules when discontinuing either medication
- For patients requiring long-term therapy, consider alternate-day dosing regimens to minimize adverse effects 4, 5
This conversion ratio of 1:1.25 (methylprednisolone:prednisone) is well-established in clinical practice and supported by high-quality evidence from multiple guidelines.