The National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health, is looking for individuals to participate in clinical studies. Participating in clinical trials allows you to play an active role in research on the nature and causes of many disorders of the brain and nervous system, and to possibly help physician-scientists develop future treatments. The information below is designed to help you quickly learn about actively recruiting research studies for which you or someone you know may be eligible.


The purpose of this trial (17-N-0076) is to study the effect of N-acetylcysteine (NAC) on brain chemistry in people with Parkinson’s disease (PD). NAC is a drug approved by the U.S. Food and Drug Administration to treat acetaminophen (Tylenol) overdose and is also available as a dietary supplement.  Many symptoms of PD are caused by the loss of brain cells that produce a chemical called dopamine.  Some research suggests that these cells are damaged by the breakdown of dopamine due to a process called oxidation.  NAC can act as an antioxidant and may protect brain cells that control movement.  In this study researchers will determine if NAC can decrease the oxidation of dopamine in people with PD.

The study will take place at the NIH Clinical Center, in Bethesda, MD.  Thirty five people with PD will be enrolled after an initial screening visit to determine eligibility.  Eligible participants will be admitted to the NIH Clinical Center for 4 to 8 days.  Participants will take a total of 5 doses of NAC orally and will undergo 2 spinal taps (lumbar punctures)—the first will occur before starting NAC, and the second will occur after taking NAC for 2 days.

Participants will receive compensation. NIH will provide travel to and from the NIH Clinical Center within the U.S. for the inpatient visit.  NIH will also provide travel and local accommodations for a medical escort if the study researchers determine it is necessary for safety.

Information gained from this study will help researchers learn more about the effect of NAC on brain chemistry, which may lead to better treatments for PD.

Eligibility Criteria:


  • 18 years of age or older
  • Taking a monoamine oxidase (MAO) inhibitor such as rasagiline (Azilect) or selegiline (Deprenyl, Eldepryl)


  • Taking levodopa/carbidopa (Sinemet)
  • Known allergy to NAC
  • Have a condition that would make it unsafe to have a spinal tap, such as spinal stenosis or myoclonus.
  • Have had headache after a spinal tap that required treatment with a “blood patch”
  • Taking a prescribed blood thinner drug, such as Coumadin or Plavix
  • Pregnant or breast-feeding
  • Have a history of alcohol or drug abuse
  • Have a medical condition that could increase risk of harm from participation based on our evaluation, such as bone marrow, liver, or kidney failure
  • Taking a medication or supplement that could interfere with the study measurements, such as entacapone (Comtan) or tricyclic antidepressants like amitriptyline (Elavil) or desipramine (Norpramin)

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