Study of NNZ-2566 in Patients With Traumatic Brain Injury

Inclusion Criteria: * Non-penetrating TBI. * Male. * Age 18-70 years. * Admission to hospital. * Post resuscitation GCS 4-12. * Have at least one reactive pupil. * Randomization within 7 hours of injury with the ability to receive investigational product within 8 hours of injury. * Hemodynamically stable after resuscitation (systolic blood pressure (SBP) \>100 mm Hg). * Willing to undergo all neuropsychological and activities of daily living (ADL) testing (i.e. understand English, able to read, write, have sufficient motor dexterity and, be available for follow-up visits at 4-6 weeks and 12-14 weeks post injury). Exclusion Criteria: * Penetrating brain injury. * Spinal cord injury. * Presence or known history of prior cerebral injury requiring hospitalization that would, in the opinion of the Investigator, interfere with or bias the assessment of efficacy. * Non-traumatic brain injury. * Known history of any medical or psychiatric disorder, or any severe concomitant disease, that in the opinion of the Investigator would interfere with or bias the assessment of efficacy. This includes the following: schizophrenia; bipolar disorder; major depressive disorder; post traumatic stress disorder (PTSD); generalized anxiety disorder; attention deficit hyperactivity disorder; neurodegenerative diseases (Alzheimer's, Parkinson's, Huntington's disease, vascular dementia, Diffuse Lewy Body Disease); stroke; brain tumor; multiple sclerosis (MS); seizure disorders; chronic pain disorder; alcoholism or substance abuse. * Significant non-central nervous system (CNS) injuries sustained at the time of the TBI that in the opinion of the Investigator would interfere with or bias the assessment of efficacy. * Weight \>150 kg. * Participation in another clinical trial within the previous 4 weeks. * Clinical state requiring greater than 6 L colloid or crystalloid fluid resuscitation prior to randomization. * Inability to obtain informed consent from legally acceptable representative. * Prior enrollment in this study. * QTc Exclusions. The study will use the exclusion criteria as defined in ICH Guideline E14 to exclude patients with a risk of QT/QTc prolongation, as follows: * A marked baseline prolongation of corrected QT/QTc interval \>450 ms. * History of risk factors for torsade de pointes (e.g. heart failure, hypokalemia (serum potassium at screening (\<3.0 mmol/L)or family history of long QT syndrome).