New and emerging treatment options for neuropathic pain

A large number of neuroanatomical, neurophysiologic, and neurochemical mechanisms are thought to contribute to the development and maintenance of neuropathic pain (NP). As a result, a corresponding wide range of treatments have been employed to treat patients with NP, including antiepileptic drugs, opioid analgesics, tricyclic antidepressants, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, N-methyl-D-aspartate receptor antagonists, cholecystokinin receptor antagonists, adenosine, lipoic acid, cannabinoids, isosorbide dinitrate, dronabinol, capsaicin, protein kinase C inhibitors, aldose reductase inhibitors, and VR-1 receptor modulators. Many of these compounds are limited by marginal efficacy and clinically significant adverse events; few have been evaluated in well-controlled, large-scale clinical trials. At present, the only agents approved for the treatment of painful diabetic peripheral neuropathy and postherpetic neuralgia are lidocaine patches 5%, duloxetine, gabapentin, and pregabalin. Of these, only pregabalin is indicated for both conditions.