Published by Practical Pain Management

As clinicians reduce their reliance on opioids for the treatment of pain, they are turning to a wider array of pharmacological tools and approaches to help overcome deficiencies of opioids, such as treatment-limiting side effects, and as aids in relieving difficult-to-treat pain conditions.

One such approach is the use of opioid antagonists. The use of opioid antagonists—in particular, naltrexone and naloxone—in chronic pain management is not new, but it deserves more recognition and acceptance than it enjoys presently.

The application of opioid antagonists, such as low- to high-dose naltrexone, is based on the notion that there are fundamental differences between the mechanisms that cause chronic and acute pain. Pain is defined by the International Association for the Study of Pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage”.

This experience, however, can be driven by different underlying physiologic and psychologic mechanisms—depending on whether the patient is experiencing acute, protective pain or a chronic, disease-state pain. Any approaches that may interrupt mechanisms underlying metamorphosis of acute pain into a chronic condition is of value. Opioid antagonists may be one such tool.