Epidural narcotic is preferred over epidural Local anaesthetic for analgesia because -

Epidural narcotics did not cause sympathetic depression or bladder dysfunction, and analgesia was segmental. The ideal opioid must cross the dura rapidly and enter the spinal cord, where it should bind with strong affinity to the opioid receptors in the substantia gelatinosa. Complications of epidural opioids even at these reduced doses still include nausea and vomiting (30-40%), sedation, respiratory depression (1%), as with parenteral routes, but to these can be added pruritus (10-50%) and urinary retention (5-40%). Pruritus is not due to histamine release but may respond to antihistamines; it will always respond to a small dose of naloxone without reducing analgesia. motor block , autonomic block not seen with epidural opioid