Is pruritis associated with epidural fentanyl (opioid analgesic)?

From the Guidelines

Yes, pruritus is associated with epidural fentanyl administration, affecting approximately 20-100% of patients who receive it. Epidural fentanyl, a commonly used opioid analgesic for pain management during labor, surgery, or postoperative care, can cause pruritus due to the activation of mu-opioid receptors in the central nervous system, particularly in the medulla, which triggers the itch sensation 1. The severity of pruritus varies among patients, with some experiencing mild discomfort while others find it extremely bothersome.

Key Points to Consider

• The mechanism behind opioid-induced pruritus involves activation of mu-opioid receptors and may also include histamine release, although fentanyl typically causes less histamine release than morphine 1.
• Treatment options for epidural fentanyl-induced pruritus include low-dose naloxone (an opioid antagonist), antihistamines like diphenhydramine, or serotonin receptor antagonists such as ondansetron 1.
• Rotating to a synthetic opioid like fentanyl may be considered if pruritus occurs with other opioids, and nonsedating antihistamines can be used before opioid administration if feasible 1.
• Importantly, the pruritus typically resolves once the epidural fentanyl is discontinued, and it does not represent an allergic reaction to the medication.

Management and Prevention

• For patients reporting previous episodes of nausea during past exposure to opioids, prevention may include pretreatment with metoclopramide or prochlorperazine around the clock for the first few days of opioid therapy, with gradual weaning of the antiemetic 1.
• Mixed agonist/antagonists such as nalbuphine alone or in combination with existing opioid can be considered, but caution is advised in patients who are opioid-tolerant as this may reduce analgesic effect or cause abstinence 1.
• Low-dose naloxone (0.25 mg/kg/h) infusion may be considered for the management of pruritus, although this should be done with caution due to the potential for reducing analgesia or inducing withdrawal symptoms 1.

From the Research

Pruritis and Epidural Fentanyl

• Pruritis is a known side effect of epidural fentanyl, an opioid analgesic used for pain management 2, 3, 4, 5, 6.
• The incidence of pruritis associated with epidural fentanyl varies, with reported rates ranging from 13% to 100% 2, 3.
• The exact mechanisms of neuraxial opioid-induced pruritus, including epidural fentanyl, remain unclear, but may involve the activation of an "itch center" in the central nervous system, medullary dorsal horn activation, and antagonism of inhibitory transmitters 2, 5, 6.
• Several pharmacological therapies have been studied for the treatment of opioid-induced pruritus, including antihistamines, 5-HT(3)-receptor antagonists, opiate-antagonists, propofol, nonsteroid antiinflammatory drugs, and droperidol 2, 4, 6.
• Opioid receptor antagonists and mixed agonist and antagonists, especially μ-opioid antagonists and κ-opioid agonists, have been shown to be effective in relieving opioid-induced pruritus 5, 6.

Management of Opioid-Induced Pruritus

• The prevention and treatment of opioid-induced pruritus remains a challenge in the field of pain management 4, 5.
• A multimodal analgesic treatment regimen combined with a mixed antagonist and κ agonists, especially μ-opioid antagonists, and κ-opioid agonists, may be the current best treatment modality for the management of opioid-induced pruritus and pain 5.
• The use of micro opioid receptor antagonists has been consistent in terms of attenuating opioid-induced pruritus, but presents problems in dose and administration 6.