Chronic opioid therapy and opioid tolerance: a new hypothesis.

Goldberg, Joel S

United States

2015-07-31T15:43:43Z

2013

Opioids are efficacious and cost-effective analgesics, but tolerance limits their effectiveness. This paper does not present any new clinical or experimental data but demonstrates that there exist ascending sensory pathways that contain few opioid receptors. These pathways are located by brain PET scans and spinal cord autoradiography. These nonopioid ascending pathways include portions of the ventral spinal thalamic tract originating in Rexed layers VI-VIII, thalamocortical fibers that project to the primary somatosensory cortex (S1), and possibly a midline dorsal column visceral pathway. One hypothesis is that opioid tolerance and opioid-induced hyperalgesia may be caused by homeostatic upregulation during opioid exposure of nonopioid-dependent ascending pain pathways. Upregulation of sensory pathways is not a new concept and has been demonstrated in individuals impaired with deafness or blindness. A second hypothesis is that adjuvant nonopioid therapies may inhibit ascending nonopioid-dependent pathways and support the clinical observations that monotherapy with opioids usually fails. The uniqueness of opioid tolerance compared to tolerance associated with other central nervous system medications and lack of tolerance from excess hormone production is discussed. Experimental work that could prove or disprove the concepts as well as flaws in the concepts is discussed.

http://www.ncbi.nlm.nih.gov/pubmed/23401765

2090-1542

https://hdl.handle.net/10161/10354

eng

Hindawi Limited

Pain Res Treat

10.1155/2013/407504

Chronic opioid therapy and opioid tolerance: a new hypothesis.

Journal article

http://www.ncbi.nlm.nih.gov/pubmed/23401765

407504

Anesthesiology

Anesthesiology, VA Anesthesiology Service

Clinical Science Departments

Duke

School of Medicine

Published

2013