The current study is a randomized (study drug assigned by chance), double-blind (neither the study doctor nor the patient knows the name of the assigned drug), placebo-controlled, dose-ranging study to evaluate the efficacy, safety, and tolerability of JNJ-42160443 in patients with postherpetic neuralgia and post-traumatic neuralgia, followed by a double blind extension and an open-label (study doctor and patient knows the name of the study drug) extension. This study will evaluate the safety and effectiveness of JNJ-42160443 in the treatment of patients with moderate to severe, chronic, neuropathic pain that is not controlled with or without standard pain therapy and who have a diagnosis of postherpetic neuralgia (PHN) or post-traumatic neuralgia. The total duration of the study will be approximately 130 weeks (i.e., includes screening phase, 12-week double-blind efficacy phase, double-blind safety extension phase, and the open-label safety extension phase). During the 12 week treatment and 40 week double-blind extension phases, PHN patients will receive Placebo, JNJ 42160443 1, 3, or 10 mg and post-traumatic neuralgia patients will receive placebo or JNJ-42160443 10 mg; all doses will be given as a single, subcutaneous (under the skin) (SC) injection every 28 days. During the 52-week open-label extension phase, all patients will receive a single SC injection of JNJ-42160443 up to 10 mg every 4, 8, or 12 weeks.
