What is the equivalent dose of hydrocortisone (HC) intravenous (IV) for prednisolone 40mg daily?

Prednisolone 40mg Daily Equivalent to Hydrocortisone IV

Prednisolone 40mg daily is equivalent to approximately 160mg of intravenous hydrocortisone daily. 1

Conversion Rationale

The conversion between oral prednisolone and intravenous hydrocortisone is based on their relative potency and bioavailability:

• Prednisolone has approximately 4 times the glucocorticoid potency of hydrocortisone
• Therefore, 40mg of prednisolone is equivalent to 160mg of hydrocortisone

This conversion is supported by clinical guidelines for perioperative management of patients on glucocorticoid therapy, where patients on prednisolone ≥5mg are managed with equivalent hydrocortisone doses during surgery and recovery 1.

Clinical Application

When converting a patient from oral prednisolone to IV hydrocortisone:

1. Dosing schedule options:

   • Continuous infusion: 160mg/24 hours
   • Intermittent dosing: 40mg every 6 hours (160mg total daily dose)

2. Administration considerations:

   • For IV bolus: Administer over 30 seconds (for smaller doses) to 10 minutes (for larger doses) 2
   • For IV infusion: Can be added to appropriate diluents (5% dextrose or normal saline) 2

Special Situations

Perioperative Management

For patients on chronic prednisolone therapy (≥5mg) undergoing surgery:

• Major surgery: Hydrocortisone 100mg IV at induction, followed by 200mg/24hr continuous infusion 1
• Intermediate surgery: Similar approach with dose tapering based on recovery 1

Stress Dosing

For patients with adrenal insufficiency or on chronic glucocorticoid therapy:

• Acute stress may require up to 100mg hydrocortisone IV followed by 200mg/24hr 1
• Critical illness: Consider hydrocortisone <400mg/day for ≥3 days 1

Common Pitfalls

1. Overestimation of equivalence:

   • Some older literature suggests higher conversion ratios, but recent evidence supports the 1:4 ratio (prednisolone:hydrocortisone) 3

2. Failure to account for diurnal variation:

   • Natural cortisol has a circadian rhythm that is difficult to mimic with standard dosing 4
   • IV hydrocortisone administration doesn't replicate normal diurnal variation

3. Inadequate stress dosing:

   • Patients on chronic glucocorticoid therapy require increased doses during physiological stress
   • Failure to increase dosing appropriately can lead to adrenal crisis

Monitoring Considerations

When transitioning between prednisolone and hydrocortisone:

• Monitor for signs of over-replacement: hypertension, hyperglycemia, fluid retention
• Monitor for signs of under-replacement: fatigue, nausea, hypotension, electrolyte abnormalities

The conversion from prednisolone 40mg to hydrocortisone 160mg IV is a standard approach based on relative potency, though individual patient response may vary based on metabolism and clinical condition.