Neuraxial infusion in patients with chronic intractable cancer and noncancer pain.

Ever since the application in 1980 of morphine for spinal analgesia in patients with refractory cancer pain, spinal infusion therapy has become one of the cornerstones for the management of chronic, medically intractable pain. Initially, spinal infusion therapy was indicated only for patients with cancer pain that could not be adequately controlled with systemic narcotics. However, over the past decade, there has been a significant increase in the number of pumps implanted for the treatment of nonmalignant pain. Indeed, "benign" pain syndromes, particularly failed back surgery syndrome, are the most common indication for intrathecal opiates. As we have gained more experience with this therapy, it has become apparent that even intrathecal opiates, when administered in the long term, can be associated with problems such as tolerance, hyperalgesia, and other side effects. Consequently, long-term efficacy has not been as significant as had been hoped. Because of the difficulties associated with long-term intrathecal opiate therapy, much of the research, both basic and clinical, has focused on developing alternative nonopioid agents to be used either alone or in combination with opiates. Clinical trials have been and continue to be conducted to evaluate drugs such as clonidine, SNX-111, local anesthetics, baclofen, and many other less common agents to determine their efficacy and potential toxicity for intrathecal therapy. This article reviews the agents developed as alternatives to intrathecal opiates.