From the Guidelines
For patients with a history of contrast-induced pruritus undergoing epidural steroid injection, a recommended pre-medication regimen includes oral diphenhydramine (Benadryl) 50mg and prednisone 40mg taken 12 hours and 2 hours before the procedure, as supported by the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention 1. This regimen is based on the principle of preventing hypersensitivity reactions by blocking histamine receptors and reducing inflammatory responses. The corticosteroid component suppresses the immune response that triggers pruritus, while antihistamines directly block the histamine-mediated itch pathway. Additionally, administering intravenous diphenhydramine 25-50mg approximately 30 minutes before contrast exposure can provide immediate protection. For patients with more severe previous reactions, consider adding famotidine (Pepcid) 20mg orally twice before the procedure, as combining H1 and H2 blockers may enhance protection, although the most recent guideline on managing reactions, including those to contrast media, suggests considering IV corticosteroid and IV H2 antagonist in the event of a reaction 1. Patients should be informed that mild drowsiness from diphenhydramine is common, and they should arrange transportation home after the procedure. Despite premedication, all patients should be monitored for breakthrough reactions for at least 30 minutes after contrast administration, as delayed reactions can still occur, following the management approach outlined for infusion reactions 1. Key considerations in managing such reactions include monitoring for signs of hypersensitivity, such as pruritus, urticaria, and hypotension, and being prepared to administer epinephrine and other supportive treatments as needed, according to the severity of the reaction classified as mild, moderate, or severe/life-threatening 1.
From the Research
Pre-Medication Regimen for Contrast-Induced Pruritus
To manage contrast-induced pruritus in a patient scheduled for an epidural steroid injection with contrast, the following pre-medication regimens can be considered:
- Antihistamine and steroid premedication, as mentioned in the study 2, can be used to prevent hypersensitivity reactions to iodinated contrast medium.
- The use of a gadolinium-based contrast agent is also an option, as discussed in the study 2, although recent publications have called for caution in its use.
Management of Opioid-Induced Pruritus
For patients undergoing epidural steroid injection, opioid-induced pruritus is a common side effect. The following treatments can be considered:
- The µ-opioid receptor antagonist naloxone or the serotonin 5-HT(3) receptor antagonist ondansetron have been shown to be effective in managing opioid-induced pruritus, as mentioned in the studies 3 and 4.
- Ondansetron, in particular, has been used to treat pruritus in patients with cholestatic diseases or renal insufficiency, suggesting that pruritus may be mediated by serotonin, as discussed in the study 4.
- The use of 5-HT3 receptor antagonists, such as ondansetron, may be a valuable treatment option for opioid-induced pruritus, as reviewed in the study 5.
Prevention and Treatment of Opioid-Induced Pruritus
A variety of medications with different mechanisms of action have been used for the prevention and treatment of opioid-induced pruritus, with mixed results, as discussed in the study 6. The current understanding of the mechanisms and pharmacological therapies available to manage opioid-induced pruritus is summarized in the study 6.