A Pharmacological Rationale to Reduce the Incidence of Opioid Induced Tolerance and Hyperalgesia: A Review

Pain Ther. 2018 Jun;7(1):59-75. doi: 10.1007/s40122-018-0094-9. Epub 2018 Mar 28.


Chronic pain is an important health and social problem. Misuse and abuse of opioids in chronic non-cancer pain management seem to be a huge problem, in some countries. This could probably affect the normal use of such analgesics in patients in need of them. Basic and clinical researches should find the solution to mitigate the potential damage. Dysregulation of mast cell and microglia activation plays an important role in the pathogenesis and management of chronic pain. Persistent mast cell activation sensitizes nociceptors and initiates central nervous system inflammatory processes, involving microglial cell activation and sensitization of spinal somatosensory neurons. Exposure of mast cells and microglia to opioids is well known to provoke activation of these non-neuronal immune cell populations, thereby contributing to an exacerbation of pro-inflammatory and pro-nociceptive processes and promoting, over the long-term, opioid-induced hyperalgesia and tolerance. This review is intended to provide the reader with an overview of the role for these non-neuronal cells in opioid-induced chronic pain and tolerance as a consequence of prolonged exposure to these drugs. In addition, we will examine a potential strategy with the aim to modulate opioid-induced over-activation of glia and mast cells, based on endogenous defense mechanisms and fatty acid amide signaling molecules.

Keywords: Chronic pain; Opioid abuse; Opioid induced hyperalgesia; Opioid induced tolerance; Opioid misuse; PEA.

Publication types

  • Review