<qa>  What is the primary outcome of the study?Probenecid at the same dose that is used as an adjunct to antibiotic therapy and NAC at the same dose that is used for acetaminophen-induced liver disease, or vehicles will be given for 3 days. The primary outcomes of the study will be the safety of drug administration and the CSF and serum levels anti-oxidant reserve AOR, with the presumption that maintaining anti-oxidant levels within the brain may prove neuroprotective. Other secondary outcomes CSF and serum probenecid, NAC, GSH and phenytoin concentrations will also be tested. Adverse events occuring during treatment with these drugs after TBI will be monitored by a local Data Safety Monitoring Board. 