Carbamazepine for the Treatment of Chronic Post-Traumatic Brain Injury Irritability and Aggression

Inclusion Criteria: * Closed head injury (defined as impaired brain function resulting from externally inflicted trauma without penetrating injury) at least 6 months prior to enrollment * Age at time of enrollment: 16 to 75 years * Voluntary informed consent of patient and informant * Subject and informant willing to comply with the protocol * Informant-rated NPI Irritability Domain score 6 or greater to include only moderate-severe irritability * Medically and neurologically stable during the month prior to enrollment If taking antidepressant, anxiolytic, hypnotic, or stimulant medications, no change anticipated in these medications during the month prior to enrollment No change in therapies or medications planned during the 42-day participation No surgeries planned during the 42-day participation Vision, hearing, speech, motor function, and comprehension sufficient for compliance with all testing procedures and assessments * Informant (e.g. family member or close friend) with daily interaction in order to observe occurrences of irritability Exclusion Criteria: * Potential subject without a reliable informant * Penetrating head injury * Injury \< 6 months prior to enrollment * Ingestion of carbamazepine during the month prior to enrollment * Inability to interact sufficiently for communication with caregiver * Acute and rehabilitation records unavailable or incomplete * Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) diagnosis of schizophrenia or psychosis * Diagnosis of progressive or additional neurologic disease * Clinical signs of active infection * Creatinine clearance \<60 mL/min * Liver function tests \> 2x normal values * Pregnancy; lactating females; sexually active females who do not agree to use birth control * Hormonal birth control as only means of birth control if sexually active and of child bearing age potential due to carbamazepine effect of lowering hormone levels, and potentially effectiveness * Concurrent use of the following medicines due to potential for drug interaction: macrolides, rifabutin, doxycycline, nicoumalone, warfarin, fluoxetine, fluvoxamine, viloxazine, nefazodone, tricyclic and tetracyclic antidepressants, clobazam, clonazepam, lamotrigine, phenytoin, sodium valproate, tigabine and topiramate, phenobarbitone, primidone, chloroquine and mefloquine, antipsychotics, indinavir, nelfinavir, saquinavir, ritonavir, diltiazem, verapamil, felodipine, isradipine, nicardipine, nifedipine, cimetidine, cyclosporins, corticosteroids, gestrinone and toremifene, danazol, tibolone * Suicidal ideation * Concurrent use of Monoamine Oxidase Inhibitors or ingestion of within 2 weeks before starting study * Hypersensitivity/allergy to carbamazepine, any of the ingredients in carbamazepine, or any structurally related drugs (e.g. the tricyclic antidepressants) * History of liver failure or hepatitis * History of renal failure * History atrio-ventricular conduction abnormalities unless paced * History of bone marrow depression * History of porphyria * Asian heritage