[NSAIDS in postoperative pain?]

Postoperative pain arises largely from distension and sectioning of nerve fibers, which generate a short-lasting but enormous afferent impulse barrage. This causes a long-lasting enlargement of receptive fields and an increase in excitability of dorsal horn neurons sending their axons up to the brain. The central process set up by extreme afferent excitation can be prevented by local anesthetics that will block afferent impulse conduction, or by premedication with opioid analgesics that will reduce the massive synaptic activation of dorsal horn neurons. Several mechanisms cause hyperactivity in these nociceptive neurons, one being an abundant formation of prostaglandins. Prostaglandins in the spinal cord facilitate the synaptic transmission from nociceptive afferents. Nonsteroidal anti-inflammatory drugs (NSAIDs) produce relief from postoperative pain by blocking the formation of prostaglandins in the spinal cord, thus abolishing the facilitatory effect of these compounds.