Active not recruitingPHASE3INTERVENTIONAL

Oral N-acetylcysteine for Retinitis Pigmentosa

This study, called NAC Attack, is looking into whether a medicine called N-acetylcysteine (NAC) can help people with an eye condition called Retinitis Pigmentosa (RP). RP is an inherited eye disease that causes cells in the back of your eye, called photoreceptors, to slowly break down. This leads to problems with night vision and a gradual narrowing of your side vision. NAC is an antioxidant, meaning it can help protect cells from damage. Previous studies in animals suggested NAC might help protect vision in RP, and a small study in people showed some promising signs. This larger study aims to find out if taking NAC over a few years can truly slow down vision loss in RP and if it is safe.

At a glance

Status

Active not recruiting

Phase

PHASE3

Sponsor

Johns Hopkins University

Enrolment target

485

Start

11 Oct 2023

Estimated completion

01 May 2030

Retinitis Pigmentosa

What is this study about?

Retinitis Pigmentosa (RP) is an inherited eye condition that causes cells in the back of your eye, called photoreceptors, to gradually break down. These cells are essential for seeing. Initially, the rod photoreceptors, which help you see in dim light and at night, are most affected. This leads to problems with night vision. Over time, the cone photoreceptors, which are responsible for your detailed vision and colour perception, also start to break down. This causes your side vision to gradually narrow, which can eventually make it feel like you're looking through a tunnel.

Scientists believe that a process called 'oxidative stress' might contribute to the damage of cone photoreceptors in RP. Think of oxidative stress as a kind of wear and tear on your cells. The medicine being tested in this study is called N-acetylcysteine, or NAC for short. NAC is known to be a strong antioxidant, meaning it can help protect cells from this kind of stress and damage.

Previous research has shown some encouraging results. In animal studies, NAC seemed to slow down vision loss in conditions similar to RP. A small study in people with RP also suggested that taking NAC by mouth for six months might lead to small improvements in some vision tests. This current large study, called NAC Attack, will involve many people at different hospitals across the UK, US, and Canada. It aims to confirm if taking NAC for a longer period, over several years, can truly help slow the progression of RP and maintain vision, and importantly, if it is safe for long-term use.

Key takeaways

This study is for people with Retinitis Pigmentosa (RP).
It's testing a medicine called N-acetylcysteine (NAC) and comparing it to a dummy pill (placebo).
NAC is thought to protect eye cells from damage.
The study aims to see if NAC can slow down vision loss over several years.
You would need to be 18-65 years old and meet specific eye health criteria to join.

Who may be eligible?

To join this study, you would generally need to be an adult between 18 and 65 years old. You should have a clear diagnosis of Retinitis Pigmentosa in both eyes, meaning you have experienced issues like night blindness and a gradual narrowing of your side vision, but you still have relatively good central vision.

The research team will also check specific measurements of your eye, such as the health of certain layers at the back of your eye and how well you can read an eye chart. Your general health is also important. For example, you wouldn't be able to participate if you have certain serious health conditions like active cancer, severe kidney or liver disease, uncontrolled high blood pressure, or a history of certain lung conditions like severe asthma or COPD. If you are female and could become pregnant, you would need to agree to use effective birth control during the study. You also wouldn't be able to take other supplements apart from Vitamin A.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 18 and 65 years old?
Do you have a diagnosis of Retinitis Pigmentosa in both eyes?
Is your central vision still relatively good (e.g., you can read fairly well)?
Do you not have active cancer or severe kidney/liver/lung disease?
Are you willing to use birth control if you are a woman who could become pregnant?
Are you able to agree not to take other supplements besides Vitamin A during the study?

Answer every question to see your result.

What does participation involve?

If you join the study, you will be taking either the study medicine (NAC) or a placebo (a dummy pill that looks like the medicine but has no active ingredients) by mouth. You won't know which one you are taking, and neither will your doctor, which helps make the results fair. This study will involve regular visits to the clinic over several years. During these visits, you'll have various eye tests to check your vision and the health of your eyes, and general health check-ups to make sure the medicine is safe for you. The exact number and frequency of visits, as well as the total length of the study, will be fully explained by the research team.

Potential risks and benefits

Taking part in this study may or may not directly benefit your health. However, the information gained from this study could help future patients with Retinitis Pigmentosa. Like all medicines, NAC can have potential side effects, and some people may experience them. The research team will monitor your health closely throughout the study to identify any potential risks. You will be given detailed information about all known risks and benefits before deciding to take part. Remember, joining a clinical trial is always voluntary, and you have the right to withdraw from the study at any time, for any reason, without affecting your usual medical care.

Locations (31)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

University of California - Davis, Department of Ophthalmology & Vision Science
Verified postcode
Davis, United States
University of Southern California, Keck School of Medicine
Verified postcode
Los Angeles, United States
University of California - San Francisco, Department of Ophthalmology
Verified postcode
San Francisco, United States
Stanford University, Byers Eye Institute
Verified postcode
Stanford, United States
Vitreo Retinal Associates
Verified postcode
Gainesville, United States
University of Florida - Jacksonville, UF Health Jacksonville
Verified postcode
Jacksonville, United States
University of Miami, Bascom Palmer Eye Institute
Verified postcode
Miami, United States
Emory University, Emory Eye Center
Verified postcode
Atlanta, United States
University Of Illinois At Chicago
Verified postcode
Chicago, United States
Northwestern University
Verified postcode
Evanston, United States
University of Iowa, Carver College of Medicine
Verified postcode
Iowa City, United States
Wilmer Eye Institute- Johns Hopkins University
Verified postcode
Baltimore, United States

Common questions

What is Retinitis Pigmentosa (RP)?

RP is an inherited eye condition where cells in the back of your eye (photoreceptors) gradually break down, leading to night blindness and a narrowing of your side vision.

What is N-acetylcysteine (NAC)?

NAC is an antioxidant medicine that may help protect cells in your eyes from damage. It's also used for other medical conditions.

What is a placebo?

A placebo is a 'dummy pill' that looks exactly like the study medicine but doesn't contain any active ingredients. It's used to compare against the active medicine.

How long will the study last?

The study will involve taking NAC or a placebo for several years, with regular clinic visits and eye assessments throughout this period.

Can I still take my regular Vitamin A supplements if I join?

Yes, unlike other supplements, the study allows patients to continue taking their standard Vitamin A supplements.