Study of Capsaicin Patch for the Management of Peripheral Neuropathic Pain

Inclusion Criteria: * patients who are 18 years of age or older aged having chronic peripheral neuropathy related with a diagnosis of either PHN or DPN * patients with chronic peripheral neuropathic pain for more than 3 months with an 11-pointed Numeric Rating Scale (NRS) pain score ≥ 4 * patients with a diagnosis of PHN were eligible if at least 3 months had elapsed since shingles vesicle crusting * patients with DPN and well controlled diabetes were asked to maintain a stable dose of oral hypoglycemic or insulin during the study period * patients taking concomitant pain medications such as anticonvulsants, antidepressants, anxiolytics, and opioids including tramadol were required to maintain a stable dose for at least 4 weeks before the study enrollment * any conservative therapies such as TENS, physical therapy, chiropractic, massage, biofeedback, or yoga were stopped at least 5 weeks before the enrollment * women of childbearing age were required to have a negative pregnancy test and were to be willing to use an effective method of contraception for at least 28 days after the last exposure to study medication Exclusion Criteria: * diffusely distributed neuropathic pain resulting from spinal stenosis, postoperative origin, complex regional pain syndrome, or genetic neurological disease, or significant pain outside the target area * significant pain of an etiology other than PHN or DNP * other severe acute or chronic medical or psychiatric condition, or laboratory abnorm…