Pharmacology of Opioid and Nonopioid Analgesics

Abstract

Summary Nociception is the ability to perceive potentially tissue-damaging energy to promote avoidance behavior and minimize the insult. Pain perception also aids in the repair of minor tissue injuries by limiting activity and splinting the injured tissue. Beyond this, more profound injuries, such as surgical insults, trigger a cascade of local inflammatory changes and neuronal activity that can be attenuated by analgesic pharmacotherapy. Continuous advances in the understanding of nociception and pharmacotherapeutics have resulted from the development of selective neurotransmitter ligands and the mapping of their receptor distribution. These endeavors delineate a set of primary physiologic and pathophysiologic adaptations in response to noxious stimuli. Architecturally, nociceptive pathways seem to be hard-wired. The dynamic functional changes of the system, when exposed to chronic noxious stimulation, however, betray the complex and often irreversible alterations in receptor expression that define central neuropathic pain. With the acknowledgment that nociceptive pathways can suffer these deleterious changes, preemptive therapy may be able not only to attenuate the nociceptive signal but also prevent the progression to chronic, recalcitrant neurogenic pain. Appreciation of currently available analgesics and an anticipation of those in development will allow for the judicious management of the pain patient.