Are opioids useful in the treatment of neuropathic pain ?
There are four unique opioids that are presumed to have enhanced efficacy for neuropathic pain syndromes. They include methadone, levorphanol, tramadol, and tapentadol. Each medication exhibits opioid agonist activity; however, each also inhibits the reuptake of norepinephrine in a similar fashion to certain antidepressants that is useful for treating neuropathic pain. Norepinephrine has demonstrated efficacy in the treatment of neuropathic pain. Methadone and levorphanol additionally inhibit N -methyl- d -aspartate (NMDA) receptors. Pure NMDA antagonists, such as ketamine, can improve neuropathic pain, and consequently medications such as methadone and levorphanol are presumed to have similar benefits. Opioids with multiple mechanisms of action should most certainly be considered in the treatment of neuropathic pain after nonopioid therapies have been exhausted, and/or as part of a rational polypharmaceutical regimen and after carefully assessing for drug interactions. In addition, studies support the use of extended release oxycodone for the treatment of neuropathic pain.