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Effects of Treatment With N- Acetylcysteine on Visual Outcomes in Patients With Retinitis Pigmentosa

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT04864496
Recruitment Status : Active, not recruiting
First Posted : April 29, 2021
Last Update Posted : April 29, 2021
Sponsor:
Information provided by (Responsible Party):
Zahra Rabbani Khah, Shahid Beheshti University of Medical Sciences

Study Description
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Brief Summary:

Retinitis pigmentosa (RP) is an inherited retinal disease with great heterogeneity. RP comprises a large group of genetic disorders causing progressive loss of vision. Despite many suggested treatments, there is actually no effective therapy for most types of RP at present. Mutations that cause RP initially lead to rod cell death. After rod photoreceptors' death, cone photoreceptors also gradually die. There are several hypotheses as to why mutation-induced rod photoreceptor cell death invariably leads to gradual dysfunction and death of cone photoreceptors resulting in severe visual acuity loss and blindness. Rods constitute 95 percent of cells in the outer retina. As they degenerate, oxygen consumption is reduced and the level of tissue oxygen markedly increases. After rods degeneration, several markers of oxidative damage appear in cones. This oxidative stress over time may lead to cone dysfunction and death. Antioxidants reduce markers of oxidative damage and promote cone function and survival. In RP, cone death occurs as a result of the death of rods, rather than as the result of the pathogenic mutations and therefore treatment with antioxidants may have the potential to be applied to all patients with RP irrespective of the disease-causing mutation.

N-acetylcysteine is a derivative of L cysteine that plays a role in the biosynthesis of glutathione and neutralizes reactive oxygen species. It also has a direct antioxidant activity via its reactive sulfhydryl agent. Its systemic use shows an acceptable safety profile. It has been shown that the use of systemic N-acetylcysteine provides significant intraocular concentration and antioxidant activity that may lead to the promotion of cone function and survival.

In a recent phase 1 randomized clinical trial (RCT), it was revealed that oral N-acetylcysteine (NAC) was safe and well-tolerated in patients with moderately advanced RP and might improve sub-optimally functioning macular cones. The authors concluded that a randomized, placebo-controlled trial is needed to determine if oral NAC can provide long-term stabilization and/or improvement in visual function in patients with RP. In this phase 2 RCT, eligible patients with the diagnosis of moderately advanced RP are randomly divided into two groups; treatment group (N-acetylcysteine tablets) and controls (placebo). Each group will be treated for 6 months. In this study, we will investigate if the use of oral N- acetylcysteine as a potent antioxidant agent can slow down or reverse the disease process in RP patients with prior moderate loss of vision. It may potentially demonstrate a treatment modality regardless of the genetic type of RP. The primary outcome measure will be the stability or improvement of the best-corrected visual acuity (BCVA). The secondary outcome measures will be changes in color vision, electroretinogram, visual field, structural OCT indices after 6 months. The same parameters will be re-evaluated 3 months after discontinuation of treatment at month 9.


Condition or disease Intervention/treatment Phase
Retinitis Pigmentosa Drug: Prescribe N-acetylcysteine tablets Drug: Prescribe placebo tablets Phase 2

Study Design
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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 30 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Effects of Oral N- Acetylcysteine on Macular Function in Retinitis Pigmentosa; a Phase 2 Randomized Controlled Trial
Actual Study Start Date : April 17, 2021
Estimated Primary Completion Date : March 1, 2022
Estimated Study Completion Date : December 20, 2022

Resource links provided by the National Library of Medicine


Arms and Interventions
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Arm Intervention/treatment
Active Comparator: Prescribe N-acetylcysteine tablets Drug: Prescribe N-acetylcysteine tablets
N-acetylcysteine tablets ,1200 mg two times daily
Placebo Comparator: Prescribe placebo tablets Drug: Prescribe placebo tablets
manufactured by Daroo Salamat Pharmed, two times daily


Outcome Measures
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Primary Outcome Measures :
  1. Change of the best corrected visual acuity (BCVA) from baseline to month 6 [ Time Frame: 6 months ]
    ETDRS chart


Secondary Outcome Measures :
  1. Change of the ellipsoid zone (EZ) width from baseline to month 6 [ Time Frame: 6 months ]
    spectral domain optical coherence tomography (SD-OCT)

  2. Changes of the wave amplitude of the flicker response from baseline to month 6 [ Time Frame: 6 months ]
    Full field electroretinograph (ffERG) testing

  3. Change of the foveal and macular sensitivity from baseline to month 6 [ Time Frame: 6 months ]
    visual field testing

  4. Change of the color discrimination parameters from baseline to month 6 [ Time Frame: 6 months ]
    D15 Fransworth 100 Hue Test


Eligibility Criteria
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Ages Eligible for Study:   18 Years to 40 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • RP patients with the best-corrected visual acuity (BCVA) between 20/30 and 20/120.

Exclusion Criteria:

  • Patients with other types of retinal dystrophy
  • Systemic or syndromic RP
  • RP patients with cystoid macular edema (CME) and the presence of cystoid changes in the foveal area
  • RP patients with other concomitant ocular diseases
  • RP patients with a history of any ocular surgery or intravitreal injection within 6 months before the study enrollment
  • RP patients who have received any supplemental drugs during the past three months before the study enrollment
Contacts and Locations
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Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04864496


Locations
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Iran, Islamic Republic of
Ophthalmic Research Center
Tehran, Iran, Islamic Republic of
Sponsors and Collaborators
Shahid Beheshti University of Medical Sciences
More Information
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Responsible Party: Zahra Rabbani Khah, Head of ophthalmic research center, Shahid Beheshti University of Medical Sciences
ClinicalTrials.gov Identifier: NCT04864496    
Other Study ID Numbers: 1400
First Posted: April 29, 2021    Key Record Dates
Last Update Posted: April 29, 2021
Last Verified: April 2021

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Additional relevant MeSH terms:
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Retinitis
Retinitis Pigmentosa
Retinal Diseases
Eye Diseases
Eye Diseases, Hereditary
Retinal Dystrophies
Retinal Degeneration
Genetic Diseases, Inborn
Acetylcysteine
N-monoacetylcystine
 Antiviral Agents
Anti-Infective Agents
Expectorants
Respiratory System Agents
Free Radical Scavengers
Antioxidants
Molecular Mechanisms of Pharmacological Action
Protective Agents
Physiological Effects of Drugs
Antidotes