- The Neuropathic Pain Special Interest Group of the International Association for the Study of Pain recently sponsored the development of evidence-based guidelines for the pharmacological treatment of neuropathic pain. Tricyclic antidepressants, dual reuptake inhibitors of serotonin and norepinephrine, calcium channel α2-δ ligands (ie, gabapentin and pregabalin), and topical lidocaine were recommended as first-line treatment options on the basis of the results of randomized clinical trials. Opioid analgesics and tramadol were recommended as second-line treatments that can be considered for first-line use in certain clinical circumstances.
- The recent approval by the US Food and Drug Administration of 2 medications—methylnaltrexone and alvimopan—introduces a new class of therapeutic entities to clinicians. These peripherally acting μ-opioid receptor antagonists selectively reverse opioid actions mediated by receptors outside the central nervous system, while preserving centrally mediated analgesia. Methylnaltrexone, administered subcutaneously, has been approved in the United States, Europe, and Canada. In the United States, it is indicated for the treatment of opioid-induced constipation in patients with advanced illness (eg, cancer, AIDS) who are receiving palliative care, when response to laxative therapy has not been sufficient.
- Neuropathic pain (NP), caused by a primary lesion or dysfunction in the nervous system, affects approximately 4 million people in the United States each year. It is associated with many diseases, including diabetic peripheral neuropathy, postherpetic neuralgia, human immunodeficiency virus-related disorders, and chronic radiculopathy. Major pathophysiological mechanisms include peripheral sensitization, sympathetic activation, disinhibition, and central sensitization. Unlike most acute pain conditions, NP is extremely difficult to treat successfully with conventional analgesics.