N-acetylcysteine (NAC) to help preserve vision in retinitis pigmentosa

NAC Attack, A Phase-3, Multicenter, Randomized, Placebo-Controlled Trial in Patents with Retinitis Pigmentosa

NIH-funded research Johns Hopkins University · NIH-11307042

This trial tests whether taking oral NAC daily can slow cone loss and help people with retinitis pigmentosa keep more vision.

Quick facts

Grant typeNIH-funded research
Study typeNIH-funded research
Funding institutionJohns Hopkins University NIH-funded
Lab location1 site (Baltimore, United States)
Project IDNIH-11307042 on NIH RePORTER

What this research studies

This is a phase 3, multicenter, randomized, double-masked trial comparing long-term oral NAC to a placebo in people with retinitis pigmentosa. Participants are randomly assigned to receive NAC or placebo, take study medication (previous work used up to 1800 mg twice daily), and come to regular clinic visits for eye imaging and vision tests. The main outcome is cone survival measured by ellipsoid zone width on OCT scans, with other functional vision measures tracked over time. About 438 participants will be enrolled across multiple centers to see if the benefits seen in animals and a small earlier human trial hold up in a larger group.

Who could benefit from this research

Good fit: People diagnosed with retinitis pigmentosa who still have measurable cone structure or function, can take oral medication, and can attend regular study visits are the likely candidates.

Not a fit: People with very advanced disease and little remaining cone tissue, or those with medical reasons they cannot take NAC, are less likely to benefit from this trial.

Why it matters

Potential benefit: If successful, long-term NAC could slow cone degeneration and help preserve visual field and acuity for people with retinitis pigmentosa.

How similar studies have performed: Animal models showed strong cone protection with antioxidants and a small 30-patient human trial found NAC was safe and produced modest short-term cone-function improvements, so this larger trial follows promising early data.

Where this research is happening

Baltimore, United States

Researchers

About this research

  1. This is an active NIH-funded research project — typically early-stage science, not a clinical trial accepting patient enrollment.
  2. Some NIH-funded labs run parallel clinical studies or seek volunteers for related work. To check, contact the principal investigator or institution listed above.
  3. For full project details, budget, and progress reports, visit the official NIH RePORTER page below.
Last reviewed 2026-06-10 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.