Key Eligibility Criteria:
- Must have had for at least 3 months painful diabetic neuropathy, or postherpetic neuralgia, or painful HIV-associated neuropathy, with moderate to severe pain on average.
- Must not have significant pain due to other causes (for example, arthritis).
- Must have intact 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 (12 weeks).
- Must not use topical pain medications on painful areas.
- Must be able to comply with study requirements such as completing daily pain diary and attending study visits and refrain from extensive travel during study participation.
- Must be at least 18 years old, not pregnant, and able to take care of self independently, with only occasional assistance if needed.
- No significant medical problems of the heart, kidneys, liver or lungs, or cancer.
- No history or current problem with substance abuse.