Physiological Dose of Prednisolone
The physiological replacement dose of prednisolone in adults is 4-6 mg per day 1.
Rationale and Context
This dosing range is based on equivalence to average daily cortisol production, which is estimated at 9-10 mg/day endogenously, with adjustments made for bioavailability 1. The 2024 joint European Society of Endocrinology and Endocrine Society guidelines explicitly define physiological daily dose equivalent as:
- Prednisolone: 4-6 mg daily
- Hydrocortisone equivalent: 15-25 mg daily
- Methylprednisolone: 3-5 mg daily
- Dexamethasone: 0.25-0.5 mg daily
Key Clinical Implications
Defining Supraphysiologic Therapy
Any dose exceeding 6 mg prednisolone daily is considered supraphysiologic 1. This threshold is clinically significant because:
- Doses >5 mg prednisone equivalent for >3-4 weeks pose risk for glucocorticoid-induced adrenal insufficiency 1
- Mortality risk increases with supraphysiologic doses (>5 mg daily), with adjusted hazard ratio of 1.97 in rheumatoid arthritis patients 1
- No increased mortality association was observed with doses ≤5 mg prednisone equivalent 1
Range Interpretation
The 4-6 mg range accounts for inter-individual variation in glucocorticoid response and metabolism 1. Recent pharmacokinetic data demonstrates that doses as low as 2-4 mg once daily can be safe and effective in most patients with adrenal insufficiency when properly monitored 2.
Important Caveats
- Prednisone and prednisolone are used interchangeably in guideline recommendations 1
- The physiological dose range represents the upper limit before adrenal suppression risk becomes significant
- Individual patient factors (age, hepatic function, disease state) may affect actual cortisol exposure even at physiological doses 3
- Elderly patients show higher prednisolone concentrations due to impaired metabolic clearance, despite paradoxically reduced sensitivity to cortisol suppression 3