Safety and Efficacy of Gabapentin in Postherpetic Neuralgia
Condition: Neuralgia,Postherpetic
MeSH terms: Neuralgia; Neuralgia, Postherpetic
Intervention: Gabapentin Extended Release tablets; Placebo
Intervention description: Once-Daily; 300 mg and 600 mg tablets; Once daily; 300 mg and 600 mg tablets
Intervention MeSH terms: Gabapentin
Phase: Phase 3
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Enrollment: 452.0
Sex: All
Minimum age: 18 Years
Healthy volunteers: No
Keywords: Postherpetic Neuralgia (PHN), shingles

Summary:

      Gabapentin and pregabalin are treatments for some types of neuropathic pain, including
      postherpetic neuralgia (PHN). However, these treatments usually need to be taken 3 times a
      day for effective pain control. The purpose of this study is to determine whether a new
      gabapentin tablet, which only needs to be taken once a day, is safe and effective for the
      treatment of postherpetic neuralgia.
    

Eligibility criteria:

        Inclusion Criteria:

          1. Men or women 18 years or older who have experienced pain for at least 6 months, but
             not more than 5 years after the healing of a herpes zoster skin rash(typically about 4
             months after the rash first appears).

          2. Patient has a pain intensity score of at least 4 on the 11-point Numerical Rating
             Scale (NRS). Patients should never be informed of the pain intensity criterion prior
             to screening or randomization.

          3. Patients of child-bearing potential must have a negative serum pregnancy test at
             screening and a negative follow-up urine pregnancy test at randomization.

          4. Patient has a mean baseline week pain intensity score of at least 4 on the 11-point
             NRS scale at the end of a 1-week baseline period and has completed at least 4 days of
             daily pain diary entries during the baseline week.

          5. Patients must have a minimum washout period of greater than 5 times the half-life of
             the drug of several medications.

          6. Patients currently treated with gabapentin pr pregabalin at screening may be eligible
             for the study, but must have a tapering period wherein the dose of gabapentin or
             pregabalin is reduced gradually over a period of 5 days followed by a two day washout
             prior to the Baseline Week.

        Exclusion Criteria:

          1. Patients who have previously not responded to treatment for PHN with gabapentin or
             pregabalin.

          2. Patients who previously experienced dose-limiting adverse effects that prevented
             titration of gabapentin to an effective dose.

          3. Patient is a nursing mother.

          4. Patient has hypersensitivity to gabapentin.

          5. Patient has had neurolytic or neurosurgical treatment for PHN.

          6. Patient has severe pain from causes other than PHN.

          7. Patient has used injected anesthetics or steroids within 30 days of baseline.

          8. Patient has skin conditions in the area affected by the neuropathy that could alter
             sensation.

          9. Patient is in an immunocompromised state.

         10. Patient has an estimated creatinine clearance less than 50 ml/min.

         11. Patient has had malignancy within past 2 years other than basal cell carcinoma.

         12. Patient has had gastric reduction surgery.

         13. Patient has severe chronic diarrhea, chronic constipation [unless attributed to drugs
             that will be washed out], uncontrolled irritable bowel syndrome (IBS) or unexplained
             weight loss.

         14. Patient has any abnormal chemistry or hematology results that are deemed by the
             investigator to be clinically significant.

         15. Patient has a history of substance abuse within the past year.

         16. Patient has a history of seizure (except for infantile febrile seizure) or is at risk
             of seizure due to head trauma.

         17. Patient has a history of chronic hepatitis B or C, hepatitis within the past 3 months,
             or HIV infection.

         18. Patient has any other clinically significant medical or psychological condition that,
             in the opinion of the Investigator would jeopardize the safety of the patient or
             affect the validity of the study results.

         19. Continuing use of any concomitant medication excluded by Inclusion Criterion 5.

         20. Patient has participated in a clinical trial of an investigational drug or device
             within 30 days of the screening visit.