• The primary endpoint is the change from Baseline to Week 6 in average daily pain as measured by an 11-point Numeric Rating Scale (NRS) derived from the patient daily diary. [ Time Frame: 6 weeks ] [ Designated as safety issue: No ]
  

• Safety endpoints include adverse events, physical exams and vital signs, neurological exams, cognition testing, clinical laboratory testing and electrocardiograms. [ Time Frame: 16 weeks ] [ Designated as safety issue: Yes ]
  
• The pharmacokinetics of RN624 will be analyzed and Anti-Drug Antibody [ADA]) testing will be done. [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  
• Secondary endpoints will examine change from Baseline for various domains of pain, and pain interference with function, using the modified Brief Pain Inventory-short form and various definitions of responder status based on the patient daily diary. [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  
• Other secondary endpoints will examine change from Baseline in the Patient's Global Assessment of Pain from Post-herpetic Neuralgia (disease activity) score and the Patient's Global Evaluation of Study Medication (treatment response) [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  
• score. [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  
• Incidence of and time to withdrawal due to lack of efficacy; and usage of rescue medication will be examined. [ Time Frame: 16 weeks ] [ Designated as safety issue: No ]
  

Inclusion Criteria:

• Male or female of any race, at least 18 years of age.
• Patients must have pain present for more than 3 months after healing of the herpes zoster skin rash.
• Has a pain score at screening that qualifies.
• Completes at least 3 average daily pain diaries during the 3 days prior to randomization and has an average pain level that qualifies.
• Body Mass Index less than or equal to 39 kg/m2.
• If female, is post-menopausal, surgically sterile, or uses adequate contraception consisting of 2 forms of birth control, one of which must be barrier method, is not lactating, and is not breastfeeding.
• Male patients must agree that female spouses/partners will use contraception as defined above or be of nonchildbearing potential (post-menopausal or surgically sterile).
• Patients must be willing and able to comply with scheduled visits, treatment plan, laboratory tests, and other study procedures.
• Patients must consent in writing to participate in the study.

Exclusion Criteria:

• Patients who cannot discontinue the use of other pain medications during the screening period and during the study.
• Disqualifying scores on questionnaires.
• Other moderate to severe pain from other conditions.
• History of allergic or anaphylactic reaction to antibodies.
• Use of biologics, including any live vaccines within 3 months of the week prior to the baseline visit.
• Unable to use acetaminophen.
• Disqualify laboratory values, Hepatitis B or C or HIV.
• Patients that have had a stroke or TIAs, dementia, epilepsy or seizures, or peripheral neuropathy from other conditions.
• Significant cardiac disease within 3 months of the study such as angina, heart attack, congestive heart failure, and other cardiac problems.
• Cancer other than basal cell or squamous cell carcinoma.
• Fails a urine test for illegal drugs including prescription drugs without a prescription.
• Plans for surgery during the study.
• History of alcoholism or drug abuse in the past two years.
• Surgery for post-herpetic neuralgia.
• Any condition that the investigator feels would put the safety of the patient at risk.