Dexamethasone 12 mg Converts to Prednisone 60 mg
The standard conversion ratio is 5:1, meaning 12 mg of dexamethasone equals 60 mg of prednisone. 1, 2
Pharmacologic Basis for Conversion
- Dexamethasone is approximately 5 times more potent than prednisone based on glucocorticoid receptor affinity and anti-inflammatory activity 1, 2
- The standard equivalence table establishes that prednisone 5 mg = dexamethasone 1 mg, making the calculation straightforward: 12 mg × 5 = 60 mg 1
- This 5:1 ratio has been validated through mechanistic models examining T-cell trafficking, neutrophil dynamics, and adrenal suppression, demonstrating reasonable dose equivalency relationships 3
Clinical Context and Important Caveats
When This Conversion Applies
- This conversion is valid for oral or intravenous administration only; intramuscular or intra-articular routes may markedly alter relative potency 1
- Both medications have excellent oral bioavailability and rapid absorption, making oral-to-oral conversions reliable 1
- The conversion maintains equivalent anti-inflammatory effects across most clinical scenarios 3
Critical Pharmacokinetic Differences
- Dexamethasone has a much longer biological half-life (36-72 hours) compared to prednisone (12-36 hours), making dexamethasone suitable for single daily dosing while prednisone may require divided doses 2, 4
- A single 12 mg dose of dexamethasone provides glucocorticoid coverage for approximately 24-48 hours, whereas 60 mg prednisone typically requires daily administration 2
- Dexamethasone has zero mineralocorticoid activity, while prednisone retains approximately 1/25th the mineralocorticoid effect of hydrocortisone 1, 2
When NOT to Substitute
- In chemotherapy-induced nausea and vomiting protocols, dexamethasone is the evidence-based standard and should not be replaced with prednisone 5, 1
- For bacterial meningitis adjunctive therapy, dexamethasone specifically (not prednisone) has been studied and is recommended 1
- In primary adrenal insufficiency requiring stress-dose coverage, dexamethasone is inadequate due to lack of mineralocorticoid activity 2
Adverse Effect Profile Differences
- Prednisone causes more fluid retention and peripheral edema due to residual mineralocorticoid activity, whereas dexamethasone does not 1
- Both agents carry similar risks for hyperglycemia, infection, and bone loss at equivalent anti-inflammatory doses 1
- Patients may experience less gastrointestinal upset with dexamethasone compared to multi-day prednisone courses 6, 7
Practical Application
- For a patient receiving dexamethasone 12 mg daily, convert to prednisone 60 mg daily if switching is clinically appropriate 1
- When converting from prednisone 60 mg to dexamethasone, use 12 mg as a single daily dose rather than divided dosing 2
- Monitor potassium levels when switching from prednisone to dexamethasone, as supplementation needs may decrease due to loss of mineralocorticoid effects 1