Low-Dose Naltrexone Co-Treatment in the Prevention of Opioid-Induced Hyperalgesia

Opioid-induced hyperalgesia (OIH) is characterized by a heightened sensitivity to pain that occurs in patients following opioid use. Prescription of opioids is currently the standard form of pain management for both neuropathic and nociceptive pain, due to the relief that patients typically report following their use. Opioids, which aim to provide analgesic effects, can paradoxically cause increasing degrees of pain among the users. The increased nociception can be either due to the underlying pain for which the opioid was initially prescribed, or other unrelated pain. As a result, those who are initially prescribed opioids for chronic pain relief may instead be left with no overall relief, and experience additional algesia. While OIH can be treated through the reduction of opioid use, antagonistic treatment can also be utilized. In an attempt to reduce OIH in patients, low doses of the opioid antagonist naltrexone can be given concurrently. This review will analyze the current role and effectiveness of the use of naltrexone in managing OIH in opioid users as described in clinical and non-clinical studies. Additionally, it seeks to characterize the underlying mechanisms that enable opioid antagonist naltrexone to reduce OIH while still allowing opioids to act as an analgesic. The authors find that OIH is a prevalent condition, and in order to effectively combat it, clinicians and patients can benefit from an extended study on how naltrexone can be utilized as a treatment alongside opioids prescribed for pain management.