What is the recommended dosing for intramuscular (IM) hydrocortisone?

Intramuscular Hydrocortisone Dosing Guidelines

For adults with adrenal insufficiency requiring intramuscular (IM) hydrocortisone, the recommended dosing is 50 mg every 6 hours when intravenous administration is not possible. 1

Adult IM Hydrocortisone Dosing

Perioperative Setting

• Major surgery/procedures under anesthesia:

  • Initial dose: 100 mg IM at induction
  • Maintenance: 50 mg IM every 6 hours while nil by mouth 1
  • Once oral intake is possible: Double usual oral maintenance dose for 48 hours, or up to a week following major surgery

• Labor and vaginal delivery:

  • Initial dose: 100 mg IM at onset of labor
  • Maintenance: 50 mg IM every 6 hours until delivery 1

Stress Dosing for Adrenal Insufficiency

• For patients with adrenal insufficiency who cannot take oral medication or receive IV hydrocortisone:
  • 50 mg IM every 6 hours (total 200 mg/24 hours) 1, 2
  • Continue until oral intake is possible or IV access is established

Pediatric IM Hydrocortisone Dosing

• Major surgery:

  • Initial dose: 2 mg/kg IM at induction 1, 2
  • Maintenance: 2 mg/kg IM every 4 hours 1

• Minor procedures requiring general anesthesia:

  • 2 mg/kg IM at induction 1, 2

Clinical Considerations

Pharmacokinetics

• IM hydrocortisone provides more reliable absorption than oral dosing during stress
• Peak levels occur approximately 1-2 hours after IM injection
• Duration of action is approximately 6-8 hours, necessitating the 6-hourly dosing schedule 3

Monitoring

• Clinical signs of adequate replacement: hemodynamic stability, absence of hypotension, normal electrolytes
• No established biomarker exists for monitoring cortisol activity 4
• When possible, transition to continuous IV infusion (200 mg/24h) which better mimics physiologic cortisol levels during stress 3

Important Caveats

• IM administration is second-line therapy when IV access is unavailable or impractical
• Continuous IV infusion is preferred over intermittent IM injections for major stress, as it better maintains cortisol concentrations in the required range 3
• Food intake delays hydrocortisone absorption, so IM doses should be administered regardless of meal timing 5
• Weight-adjusted dosing reduces interpatient variability in cortisol exposure, particularly important in pediatric patients 5
• Patients with "inadequate" endogenous steroid production may be more sensitive to the hemodynamic effects of hydrocortisone therapy 6

Special Populations

• Trauma patients: May benefit from a continuous infusion regimen (200 mg/day for 5 days, followed by 100 mg on day 6 and 50 mg on day 7) 7
• Septic patients: Initial bolus of 50-100 mg followed by continuous infusion is preferred over intermittent bolus administration 3

Remember that all patients on chronic hydrocortisone therapy need education on stress dosing for emergency situations and should wear medical alert identification 2.