 20. Patients on any of the following known hepatotoxic agents: Antioxidant N-acetly-cysteine Mucomyst, Acetadote, Fluimucil, Parvolex, Niacin nicotinic acid, Dantrium dantrolene, Naizide isoniazid, Normodyne labetalol, Cylert pemoline, Felbatol felbamate, Zyflo zileuton, Tasmar tolcapone, or Trovan trovafloxacin. Patients must have been off the aforementioned medications for a minimum of two weeks prior to randomization 