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Study on the Effects of Oral N-Acetylcysteine for Patients with Retinitis Pigmentosa

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the effects of a treatment for Retinitis Pigmentosa, a genetic disorder that affects the eyes and can lead to vision loss. The treatment being tested is an oral medication called N-Acetylcysteine (NAC), which is taken in the form of effervescent tablets. The study will compare the effects of NAC with a placebo to see if NAC can help maintain visual function and reduce visual disability in patients with this condition.

The purpose of the study is to evaluate how effective and safe NAC is when taken twice a day over a period of 45 months. Participants will be randomly assigned to receive either the NAC treatment or a placebo, and neither the participants nor the researchers will know who is receiving which treatment. This approach helps ensure that the results are unbiased. Throughout the study, participants will have regular check-ups to monitor their vision and overall health.

Participants will undergo various assessments to measure changes in their vision, including tests that evaluate the sensitivity of the macula, which is the central part of the retina responsible for detailed vision. The study aims to determine if NAC can slow down the progression of vision loss compared to the placebo. By the end of the study, researchers hope to gather valuable information about the long-term safety and effectiveness of NAC for individuals with Retinitis Pigmentosa.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, you will be asked to provide informed consent. This means you agree to participate after understanding the study's purpose and procedures.

    You must be between 18 and 65 years old and willing to follow the study protocol, including attending all study visits and assessments.

  2. Step 2

    Initial assessment

    An initial assessment will be conducted to establish a baseline for your visual function. This may include tests like spectral domain-optical coherence tomography (SD-OCT) to measure the width of a specific part of your eye.

    You will also undergo tests to measure your macular sensitivity and visual acuity using specific protocols.

  3. Step 3

    Medication administration

    You will be randomly assigned to receive either the study medication, N-acetylcysteine (NAC), or a placebo. The medication is in the form of effervescent tablets to be dissolved in water.

    The dosage is 1800 mg of NAC, taken twice a day. This will continue for a duration of 45 months.

  4. Step 4

    Ongoing assessments

    Throughout the study, regular assessments will be conducted to monitor your visual function and overall health.

    These assessments will include repeated measurements of your eye's specific parts and tests for macular sensitivity and visual acuity.

  5. Step 5

    Completion of the study

    At the end of the 45-month period, a final assessment will be conducted to evaluate the long-term effects of the medication on your visual function.

    The study aims to determine if the medication helps maintain visual function and reduce visual disability in patients with retinitis pigmentosa.

Who can join the trial?

5 criteria

  • Ability and willingness to provide informed consent (agreeing to participate after understanding the study details).
  • Age between 18 and 65 years at the time of signing the Informed Consent Form.
  • Ability and willingness to follow the study plan and attend all study visits and assessments, as judged by the study doctor.
  • If you can have children, willingness to use a method of contraception (a way to prevent pregnancy).
  • Agreement not to take supplements other than vitamin A.

Who cannot join the trial?

7 criteria

  • Patients who are not diagnosed with Retinitis Pigmentosa cannot participate. This is a condition that affects the eyes and can lead to vision loss.
  • Patients who are under 18 years old cannot participate.
  • Patients who are pregnant or breastfeeding cannot participate.
  • Patients who have participated in another clinical trial within the last 30 days cannot participate.
  • Patients who have a known allergy to the study medication cannot participate.
  • Patients who have a serious medical condition that might interfere with the study cannot participate.
  • Patients who are unable to follow the study procedures cannot participate.
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Investigated drugs

N-Acetylcysteine is a medication being tested in this clinical trial to see if it can help people with a condition called retinitis pigmentosa. This condition affects the eyes and can lead to vision loss. The trial is looking at whether taking N-Acetylcysteine by mouth can help maintain vision and reduce the disability caused by this condition. The study will also check if it is safe to use this medication over a long period. N-Acetylcysteine is thought to work by protecting the cells in the eyes from damage, which might help preserve vision in people with retinitis pigmentosa.

What is already known about the treatment

N-Acetylcysteine (NAC) – N-Acetylcysteine is administered orally in the form of tablets, taken twice a day at a dose of 1800 mg. It is currently being studied in a Phase III clinical trial to assess its effectiveness and safety for patients with Retinitis Pigmentosa, a condition that affects vision. The main goal is to see if NAC can help maintain visual function and reduce visual disability over a long period. NAC works by acting as an antioxidant, which helps protect cells from damage. It is classified as a mucolytic agent, which means it helps break down mucus, but in this context, its antioxidant properties are being explored for eye health.

Investigated diseases

Retinitis Pigmentosa – Retinitis Pigmentosa is a group of genetic disorders that affect the retina's ability to respond to light, leading to a gradual decline in vision. It typically begins with night blindness, followed by a loss of peripheral vision, and eventually can lead to a decrease in central vision. The disease progresses as the photoreceptor cells in the retina, known as rods and cones, deteriorate over time. This degeneration causes the characteristic symptoms of the disease, including tunnel vision and difficulty seeing in low-light conditions. The rate of progression can vary significantly among individuals, with some experiencing a slow decline and others a more rapid loss of vision. The condition is often diagnosed in adolescence or early adulthood, but symptoms can appear at any age.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2022-501438-46-00Estimated enrolment498 patientsSponsorJohns Hopkins University

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