Which technique is least effective in treating pruritus from neuraxial opioids?

Which technique is least effective in treating pruritus from neuraxial opioids?

• A. Nalbuphine 5 mg IV
• B. Dexmedetomidine 30 μg IV
• C. Diphenhydramine 50 mg IV
• D. Hydroxyzine 20 mg IM

Answer: (B)

Pruritus from neuraxial opioids is driven mainly by mu-receptor activation in the central itch pathways, not primarily by histamine release. That’s why approaches that directly counteract mu-opioid activity tend to be more effective. Nalbuphine, as a mu-antagonist and kappa-agonist, blocks the mu-receptor–mediated itch and typically provides clear relief. Antihistamines like diphenhydramine and hydroxyzine can help some patients, largely through sedative effects and non-specific anti-pruritic actions, but they often don’t fully address the itch since it isn’t primarily histamine-driven. Dexmedetomidine, an alpha-2 adrenergic sedative, does not directly oppose mu receptor–driven itch, so its impact on neuraxial opioid–induced pruritus is limited, making it the least effective option for this purpose.

Pruritus from neuraxial opioids is driven mainly by mu-receptor activation in the central itch pathways, not primarily by histamine release. That’s why approaches that directly counteract mu-opioid activity tend to be more effective. Nalbuphine, as a mu-antagonist and kappa-agonist, blocks the mu-receptor–mediated itch and typically provides clear relief. Antihistamines like diphenhydramine and hydroxyzine can help some patients, largely through sedative effects and non-specific anti-pruritic actions, but they often don’t fully address the itch since it isn’t primarily histamine-driven. Dexmedetomidine, an alpha-2 adrenergic sedative, does not directly oppose mu receptor–driven itch, so its impact on neuraxial opioid–induced pruritus is limited, making it the least effective option for this purpose.