Prednisone to Prednisolone Conversion
4 mg of prednisone is equivalent to 4 mg of prednisolone—the doses are essentially 1:1 for practical clinical purposes. 1
Standard Dose Equivalence
- Prednisone 5 mg and prednisolone 5 mg have equivalent anti-inflammatory potency, meaning the conversion ratio is approximately 1:1. 1
- For your specific question: 4 mg prednisone = 4 mg prednisolone. 1
- This 1:1 equivalence applies to both oral and intravenous formulations. 1
Critical Consideration: Liver Disease
In patients with significant liver disease, prednisolone should be strongly preferred over prednisone, even though the nominal dose remains the same. Here's why this matters clinically:
Impaired Conversion in Liver Disease
- Prednisone is a prodrug that requires hepatic 11β-hydroxysteroid dehydrogenase to convert it to the biologically active prednisolone. 2, 3
- Patients with active liver disease (elevated bilirubin and transaminases) show significantly impaired conversion of prednisone to prednisolone, resulting in lower levels of active drug. 2
- In cirrhotic patients with severely impaired liver function, mean serum prednisolone concentrations after oral prednisone were only 53% of those in patients with mildly impaired function. 3
- Conversely, serum prednisone concentrations (the inactive form) were 74% higher in patients with severe liver dysfunction. 3
Clinical Implications
- For patients with active hepatitis, cirrhosis, or elevated liver enzymes: prescribe prednisolone directly rather than prednisone. 2, 3
- When prednisolone is given directly (bypassing the need for hepatic conversion), serum levels are independent of liver function. 3
- The impaired conversion can lead to treatment failure if prednisone is used in patients with severe liver disease. 2
Important Nuance
- Some studies suggest that even in severe chronic active liver disease, the conversion may still be adequate for clinical effect, with rapid interconversion equilibrium between the two drugs. 4, 5
- However, the weight of evidence favors using prednisolone directly in patients with impaired liver function to ensure predictable drug levels. 3, 6
- Additional factors in liver disease include decreased protein binding (leading to higher free prednisolone levels) and prolonged half-life, which can increase both efficacy and toxicity risk. 2, 6
Practical Prescribing Algorithm
- Normal liver function: Either prednisone 4 mg or prednisolone 4 mg is acceptable. 5
- Active liver disease (elevated AST/ALT, bilirubin) or cirrhosis: Use prednisolone 4 mg directly. 3
- Severe liver impairment: Strongly prefer prednisolone 4 mg and monitor closely for both efficacy and adverse effects due to altered pharmacokinetics. 2, 6