Levorphanol for the treatment of severe chronic pain.

The search for an effective and affordable treatment for severe chronic pain, particularly neuropathic pain, has been elusive. The reluctance of many physicians to prescribe strong opioids for pain when other modalities have failed has resulted in the undertreatment of many patients. Levorphanol is 1 of 2 opioids that block N-methyl-D-aspartate receptors. In this article, the mechanism of N-methyl-D-aspartate receptor activation is described, the efficacy of levorphanol in the treatment of severe chronic pain is examined, and the properties and clinical applications of that agent are reviewed. Other N-methyl-D-aspartate receptor antagonists are commented upon, and the outcome of treatment with levorphanol in chronic-pain patients is described in detail.