The study protocol of a randomized, double-blind, placebo-controlled add-on phase 2 trial testing N-acetyl cysteine as a neuroprotective agent in progressive multiple sclerosis (MS) has been published in the journal Contemporary Clinical Trials.

“The add-on design of an oral therapy allows easy implementation in clinical practice,” the study authors wrote.

The study was approved by the Institutional Review Board at the University of California, San Francisco, and an Investigational New Drug approval was obtained from the US Food and Drug Administration.

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The aim of the trial is to assess the safety, tolerability, and effect of N-acetyl cysteine on the progression of progressive MS using several magnetic resonance imaging (MRI), clinical, and biological markers.

The multisite, parallel-group trial aims to enroll 98 participants with progressive MS, 40 to 70 years of age, with an Expanded Disability Status Scale score between 3 and 7.

Participants will be divided into 2 groups and will either receive 1200 mg of N-acetyl cysteine or a placebo, 3 times a day. During the 15-month intervention period, this will be an add-on to the standard treatment stratified by site and type of disease.

The primary outcome measures are the safety and tolerability of the add-on treatment as measured by the number of adverse events and the effect of the add-on treatment on the progression of the brain, thalamic, and cervical cord atrophy as measured by brain and cervical spine MRI at 3 and 15 months.

The secondary outcome measure is the clinical effect of the treatment as measured by the 9-hole peg test, 25-foot walk test, and symbol digit modalities test. 

Another outcome measure is the effect of the treatment on disease progression, which will be monitored using imaging metrics and changes captured by a wearable multisensor device.

The trial is currently recruiting participants at the University of California in San Francisco. It started on February 16, 2022, and is estimated to be completed in February 2025.

N-acetyl cysteine is a glutathione precursor with antioxidant properties. It is thought that a reduction in oxidative stress injury can reduce brain atrophy. 


Schoeps VA, Graves JS, Stern WA, et al. N-acetyl cysteine as a neuroprotective agent in progressive multiple sclerosis (NACPMS) trial: study protocol for a randomized, double-blind, placebo-controlled add-on phase 2 trial. Contemp Clin Trials. 2022;28;122:106941. doi:10.1016/j.cct.2022.106941

Neuroprotection with N-acetyl cysteine for patients with progressive multiple sclerosis (NACPMS). US National Library of Medicine. Updated April 4, 2022. Accessed October 12, 2022.