A Study to Evaluate the Efficacy, Safety, and Tolerability of JNJ-42160443 in Patients With Neuropathic Pain (Postherpetic Neuralgia and Post-traumatic Neuralgia)

The purpose of this study is to evaluate the safety and effectiveness of JNJ-42160443 in the treatment of moderate to severe neuropathic pain in patients with a diagnosis of postherpetic neuralgia and post-traumatic neuralgia.

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.

Eligibility Criteria:
Inclusion Criteria:

Patients diagnosed with postherpetic neuralgia or post-traumatic neuralgia and who have chronic neuropathic pain (pain persistent for \> 6 months) that is moderate to severe; Currently taking pain medication but are not adequately controlled by standard of care or are not currently taking pain medications because intolerable to, or not willing to use, standard of care. Exclusion Criteria: History of a separate pain condition (e.g., joint osteoarthritis) that is more severe than pain due to diagnosis of PHN or post-traumatic neuralgia

* Patients with post-traumatic neuralgia that are characteristic of complex regional pain syndrome Type I
* Patients with lumbar-sacral radiculopathy, failed low-back surgery, or spinal cord injury
* Patient whose nerve injury or pain is expected to recover in the next 4 months
* Patients with evidence of another neuropathic pain not under study, such as pain resulting from diabetic painful neuropathy, sensory neuropathies or pain caused by radiation, chemotherapy, alcohol, HIV infection
* Other peripheral neuropathy, paresthesia, or dysesthesia, or any other previously diagnosed neurologic condition causing the above noted symptoms that is not related with the PHN or post-traumatic neuralgia under the study
* Women who are pregnantHistory of a separate pain condition (e.g., joint osteoarthritis) that is more severe than pain due to diagnosis of PHN or post-traumatic neuralgia; Patients with post-traumatic neuralgia that are characteristic of complex regional pain syndrome Type I; Patients with lumbar-sacral radiculopathy, failed low-back surgery, or spinal cord injury; Patient whose nerve injury or pain is expected to recover in the next 4 months; Patients with evidence of another neuropathic pain not under study, such as pain resulting from diabetic painful neuropathy, sensory neuropathies or pain caused by radiation, chemotherapy, alcohol, HIV infection; Other peripheral neuropathy, paresthesia, or dysesthesia, or any other previously diagnosed neurologic condition causing the above noted symptoms that is not related with the PHN or post-traumatic neuralgia under the study; Women who are pregnant or breast-feeding; Type I or Type II diabetes.