NGX-4010 for the Treatment of Postherpetic Neuralgia

Key Eligibility Criteria: * Must be diagnosed with PHN and be at least 6 months after crusting of the skin vesicles, with moderate to severe pain. * Must not have significant pain due to causes other than PHN (for example, arthritis). * Painful areas should not be located on the face, above the hairline of the scalp, and/or in proximity to mucous membranes. * Must have intact and unbroken skin at the treatment area. * Must be prepared to remain on the same pain medications at the same doses as before the study for the entire duration of the study (1-year). * Must not have any implanted medical device (spinal cord stimulator, intrathecal pump or peripheral nerve stimulator) for the treatment of pain. * Must not use topical pain medications for PHN. * Must be able to comply with study requirements such as completing a daily pain diary, attending study visits and refraining from extensive travel during study participation. * No significant medical problems of the heart, kidneys, liver or lungs, or cancer. * No history or current problem with substance abuse.