A 48-year-old woman with a prior moderate urticarial reaction to iodinated contrast needs an urgent contrast-enhanced CT within the next few hours. There is no time for the standard 13-hour oral premedication protocol. What is the MOST appropriate accelerated premedication regimen?
- A Hydrocortisone 100 mg orally 30 minutes before the scan
- B Prednisolone 50 mg orally immediately before the scan only
- C Methylprednisolone 40 mg IV every 4 hours until the scan, plus diphenhydramine 50 mg IV 1 hour before ✓
- D Adrenaline 0.3 mg intramuscularly 15 minutes before the scan
Correct answer: C. Methylprednisolone 40 mg IV every 4 hours until the scan, plus diphenhydramine 50 mg IV 1 hour before
Explanation
When imaging cannot be delayed 13 hours, the accepted accelerated alternative is intravenous methylprednisolone 40 mg or hydrocortisone 200 mg given every 4 hours until the study, combined with an antihistamine 1 hour beforehand. Corticosteroids need several hours to suppress mediator release, so a single dose given immediately before injection provides no protection, which eliminates options B and A. Prophylactic adrenaline is not recommended for routine premedication.
Reference: ACR Manual on Contrast Media, current edition ed.
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Written and medically reviewed by the StethoPrep medical team.