To Evaluate the Efficacy and Safety of TYNADOTE® in the Treatment of Acetaminophen Overdose

This will be a 21-day study to evaluate the efficacy and safety of TYNADOTE® in the treatment of acetaminophen overdose. After the inform consent is obtained from the subject or his/her legal guardians, the designated assessment will be performed. Subjects who fulfill all the inclusion and exclusion criteria will be eligible to enter the study. Except standard NAC antidote therapy, subjects would be randomized as 1:1 ratio to combine oral TYNADOTE® or placebo. Eligible subjects will be randomized to receive oral TYNADOTE®/placebo combined iv NAC, and the regimen was listed as below: The NAC intravenous loading dose is 150 mg/kg over a period of 15 to 60 minutes, followed by an infusion of 12.5 mg/kg per hour over a 4-hour period, and finally an infusion of 6.25 mg/kg per hour over a 16-hour period. Study drug, TYNADOTE® /placebo, should be given a loading dose of 400 mg, followed by 17 maintenance doses of 200 mg every 4 hours (Day 1 to Day 3). During the treatment period, vital signs will be checked 15 minutes prior to dosing, 30 minutes, 60 minutes, then 2, 4, 8, 12, 24, 36, 48, 60 and 72 hours after first dosing. Blood samples will be collected for liver injuries and function test, including AST, ALT, total bilirubin, direct bilirubin and prothrombin time (INR), prior to dosing, 4 hours, 12 hours, 24 hours, 36 hours, 48 hours, 60 hours, 72 hours after first dosing. Blood samples for drug/metabolites concentration, including TYNADOTE® plasma concentration (trough level), plasma acetaminophen concentration, AAP-Cys and AAP-Cys adducts concentration, prior to dosing, 4 hours, 12 hours, 24 hours, 36 hours, 48 hours, 60 hours and 72 hours after first dosing. Blood samples for biochemistry and hematology, Day 1-3. After completing the treatment (Day 3), subject will conduct the following evaluations before discharge: * Review of adverse events * Review of concomitant medications * Physical examination On Day 7 and Day 21, subjects should return to the clinics for liver injuries/function follow up and reviewing the adverse events.