Patient description: A 53-year-old man presents with chronic HCV infection for the past 2 years. His past medical history is only significant for inguinal hernia surgery when he was 20 years old. He is on IFN (100 mg/week) plus RBV (400 mg/day) combination therapy for the past 9 months. Direct antiviral drugs were added to his treatment 6 months ago. His medical record shows previous positive HCV RNA tests as well as positive enzyme immunoassay for anti-HCV-antibodies. The recent biopsy was negative for hepatocellular carcinoma and was only remarkable for chronic inflammation compatible with a chronic viral hepatitis. There is no evidence of alcoholic liver disease, bleeding from esophageal varices, hemochromatosis, autoimmune hepatitis or metabolic liver disease. He is an alert male with no acute distress. His BP: 130/75, HR: 90/min and BMI: 27. His abdomen is soft with no ascites or tenderness. The lower extremities are normal with no edema.

Clinical trial eligibility criteria: eligible ages (years): 18.0-65.0,  Acute Liver Failure Acute Liver Injury Men and women, ages 18-65 (have not reached their 66th birthday). 2. Acute liver failure, defined as the development of coagulopathy (International normalized ratio [INR] ≥1.5) with encephalopathy in a patient with no prior history of liver disease, with onset of symptoms within 28 days of the inciting event. Patients may have either a history of acetaminophen overdose (defined as >4 g/day within 7 days of presentation) and/or detectable acetaminophen levels in the serum, with a pattern of liver function tests typical for acetaminophen toxicity (bilirubin < 10 mg/dL and alanine aminotransferase (ALT) ≥1000 IU/L), or a diagnosis of hepatitis A, hepatitis B, drug-induced liver injury, autoimmune hepatitis or indeterminate cause based on standard criteria. 3. ALI patients may also be enrolled (those meeting the above plus coagulopathy (INR ≥ 2.0) and no evidence of encephalopathy) 4. Written informed consent from the patient (ALI) or patient's legally authorized representative or family member if he/she is considered encephalopathic (ALF). 5. Ammonia level ≥60 μmol/L at baseline (within 8h prior to T0/initiation of infusion). 6. Serum creatinine levels as follows: 1. Cohort 1: Creatinine ≤1.5 mg/dL; and 2. Cohort 2: Creatinine >1.5 mg/dL and <10mg/dL. 7. Mean arterial pressure of >65 mmHg  History of chronic liver disease. 2. Signs of overt cerebral herniation, or uncontrolled intracranial hypertension by intracranial pressure (ICP) monitoring (if applicable). 3. Evidence of Wilson's disease, alcoholic hepatitis, biliary obstruction, ischemic hepatitis, severe acute renal tubular necrosis (ATN) due to shock, or any patient with ongoing hypotension. 4. Significant gastrointestinal bleeding (coffee grounds per nasogastric tube and/or melena). 5. Hemodynamic instability, defined by a mean arterial pressure of <65 mmHg. 6. Cardiopulmonary complications such as pulmonary edema, aspiration pneumonia, heart failure. 7. QT interval of >500msec at baseline EKG. 8. Pregnancy. 9. History of malignancy that has not been cured or any cancer in remission for less than 1 within the past 5 year. Non-melanoma skin cancers do not preclude participation in the trial. 10. Concomitant administration of drugs known to interfere with renal excretion of phenylacetylglutamine or those medications that may induce hyperammonemia such as haloperidol, valproic acid and systemic corticosteroids (prohibited during the study). Alternative ammonia modifying agents such as lactulose and rifaximin are not considered standard of care and are prohibited during the study period. 11. Any other health condition that would preclude participation in the study in the judgment of the principal investigator