Inclusion Criteria:

• Patient has moderate to severe nerve pain due to one of the following conditions: Postherpetic neuralgia, Painful diabetic neuropathy, Small fiber neuropathy or idiopathic distal sensory polyneuropathy
• Patient is able to complete questionnaires in either English or Spanish
• Patient is at least 18 years of age

Exclusion Criteria:

• Patient is either pregnant or breastfeeding
• Patient has a history of angioedema (swelling beneath the skin surface) or peripheral edema (foot, leg, and/or ankle swelling)
• Patient has a history of congestive heart failure
• Patient has a seizure disorder
• Patient has a history of drug and/or alcohol abuse within the past 1 year
• Patient failed treatment due to lack of pain relief with more than three drugs for nerve pain
• Patient has had cancer (except basal cell carcinoma) within the past two years
• Patient anticipates the need for surgery while participating in the study
• Patient has a reported history of hepatitis B, C, or HIV infection
• Patient has another type of pain that is more painful than the nerve pain
• Patient has generalized anxiety disorder, untreated depression, psychosis, or post-traumatic stress disorder
• Patient is involved in litigation or receives worker's compensation related to nerve pain