A study of EMA401 in the treatment of pain due to nerve injury.

INTERVENTION: EMA401 100mg orally twice a day for 28 days As this is a crossover design all patients will receive both EMA401 and placebo (in either order), with a 2 week washout period between each treatment CONDITION: Peripheral neuropathy due to nerve injury PRIMARY OUTCOME: To determine the efficacy of 100 mg EMA401 orally twice daily for 28 days in reducing mean pain intensity score in patients with neuropathic pain due to peripheral nerve injury, compared to placebo. ; ; This will be assessed using patient pain scores (on a scale of 0 to 10, where 0 = no pain and 10 = pain as bad as you can imagine). SECONDARY OUTCOME: To evaluate the efficacy of 100 mg EMA401 orally twice daily for 28 days on psychophysical measures of sensitisation in pain pathways in patients with neuropathic pain due to peripheral nerve injury, compared to placebo. ; ; This will be assessed by change in area of evoked pain from using brush, monofilaments, and thermal thresholds, patient pain scores, patient and clinician ratings of change, and patient questionnaires (specifically the Short Form McGill Pain Questionnaire, the Insomnia Severity Index, and the Brief Pain Inventory) To evaluate the potential efficacy of EMA401 using several alternate endpoints, including onset and maintenance of effect, responder rate, and time to 30% reduction in pain intensity To evaluate the safety and tolerability of 100 mg EMA401 orally twice daily for 28 days in patients with neuropathic pain due to peripheral nerve injury. ; ; This will be assessed by incidence and severity of adverse events, and changes and findings in laboratory parameters, physical and neurological examinations, vital signs, and ECG. All adverse events that occur will be measured by recording details of the event including description, start and stop dates, severity, seriousness, and relationship to study drug INCLUSION CRITERIA: Patients who: 1. Are able to give voluntary written informed consent to participate in the study. 2. Are 18 to 80 years old inclusive. 3. Have had focal peripheral neuropathic pain for least 3 months prior to Screening that is related to nerve injury caused by trauma or surgery not associated with ongoing infection (examples include post‐thoractomy syndrome, post‐mastectomy syndrome, post‐inguinal herniorrhaphy syndrome, post‐radical neck dissection syndrome, traumatic neuropathies (bullet wounds, lacerations, road traffic accidents)). 4. Have a location of pain consistent with the area innervated by the affected nerve(s), with or without other sensory symptoms in the affected area. 5. Be diagnosed as suffering from moderate to severe pain across the Screening period. The assessment of moderate and severe pain will be made using an algorithm proprietary to Spinifex Pharmaceuticals. The investigator will be informed immedi