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Amiloride Clinical Trial In Optic Neuritis (ACTION)

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. Identifier: NCT01802489
Recruitment Status : Completed
First Posted : March 1, 2013
Last Update Posted : May 17, 2018
Multiple Sclerosis Society of Great Britain and Northern Ireland
Information provided by (Responsible Party):
University of Oxford

Brief Summary:

Optic neuritis (ON) is a common event in Multiple Sclerosis (MS), and causes significant loss of nerve cells in the eye, resulting in poor vision. Optic neuritis also provides a sensitive way of testing the effectiveness of drugs that may help protect from loss of nerve cells in ON and therefore in MS.

The investigators have identified through laboratory and early clinical research in humans that amiloride (a water tablet already in use) may be a drug that can be of benefit in optic neuritis by protecting from loss of nerves cells, ie a neuroprotective drug.

The purpose of this study is to assess the efficacy of amiloride as a neuroprotective drug in optic neuritis

Condition or disease Intervention/treatment Phase
Optic Neuritis Multiple Sclerosis Drug: Amiloride Drug: Placebo Phase 2

Detailed Description:

Multiple sclerosis (MS), an inflammatory condition of the nervous system, is the most common cause of disability in people of working age in the western world. In addition to the inflammatory episodes in MS, axonal and neuronal damage occurs. It is this axonal loss which is thought to be the major pathological substrate for disability in MS.

Acute inflammatory demyelinating optic neuritis is a common event in multiple sclerosis. Following optic neuritis there is axonal loss in the optic nerve and retina, which if severe can result in a poor visual recovery. Uniquely amongst central nervous system (CNS) structures, the structural and functional changes in the eye during and following optic neuritis provide a sensitive way of observing neurodegeneration and testing the effectiveness of potential neuroprotective agents. In optic neuritis it has been shown that thinning of the retinal nerve fibre layer takes place, and by 6 months this thinning is established and has largely stabilised. This represents axonal loss in the anterior visual system. The degree of this thinning has been shown to correlate with the amount of vision recovered following optic neuritis, the more thinning that occurs, the poorer the outcome. The thickness of the retinal nerve fibre layer can be measured by the simple scanning techniques of scanning laser polarimetry (GDx) and optical coherence tomography (OCT).

Axonal loss in MS is likely to be multifactorial, but a key end point is the influx of sodium and calcium ions. Recent research suggests that in the inflammatory environment of optic neuritis, the acid sensing ion channel may have an important role in this influx of sodium and calcium, and therefore in axonal loss in MS. The drug amiloride, already in use as a diuretic, is a known blocker of this ion channel. The investigators have identified through laboratory and early clinical research in humans that by blockade of the acid sensing ion channel, amiloride may be neuroprotective in optic neuritis and MS.

The investigators primary objective is to assess the neuroprotective efficacy of amiloride in optic neuritis through the surrogate measure of retinal nerve fibre layer measurement. Secondary objectives are to assess markers of neurodegeneration in ON and the neuroprotective effect of amiloride through non-conventional MRI outcomes, to assess if amiloride improves functional and visual outcome following optic neuritis, and to confirm optic neuritis as a sensitive and efficient model for neuroprotection in a clinical trial framework.

46 Participants will be recruited to receive either amiloride, or an identical placebo capsule for 5 months. The primary outcome will be measured at 6 months, with a further measure at 12 months.

Should this trial show a significant benefit from amiloride in optic neuritis, it will be an important first step in developing neuroprotective therapies in optic neuritis and MS and potentially this could have a significant impact on people with MS and their carers.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 46 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: A Double Blind Randomised Control Trial on Neuroprotection of Amiloride in Optic Neuritis
Study Start Date : February 2013
Actual Primary Completion Date : November 2015
Actual Study Completion Date : November 2015

Arm Intervention/treatment
Active Comparator: Amiloride
Amiloride capsules 10mg once per day for 5 months
Drug: Amiloride
Other Name: Midamor

Placebo Comparator: Placebo
Placebo capsules one per day for 5 months
Drug: Placebo
Placebo capsule identical in appearance to Amiloride 10mg capsule

Primary Outcome Measures :
  1. Scanning laser polarimetry determined retinal nerve fibre layer thickness [ Time Frame: Baseline, 6 and 12 months ]

    The primary outcome will be difference in retinal nerve fibre thickness at 6 months between affected eye and non-affected fellow eye at baseline between the amiloride and placebo group.

    An additional measure will be made at 12 months

Secondary Outcome Measures :
  1. Optical coherence tomography determined difference in retinal nerve fibre layer thickness. [ Time Frame: Baseline, 6 and 12 months ]
    Difference in thickness at 6 months and 12 months between affected eye and non-affected fellow eye at baseline, between the amiloride and placebo group

  2. Differences between the amiloride and placebo groups in non-conventional MRI surrogate marker of white matter and grey matter injury and connectivity by 3T scanning. [ Time Frame: Baseline, 6 and 12 months ]
    • Diffusion weighted imaging (DWI) - measures; fractional anisotropy (FA), mean diffusivity (MD), axial and radial diffusivity (RD) of the posterior visual tracts
    • High Resolution T1-weighted image measure of grey matter volume
    • Magnetic resonance spectroscopy (MRS) measures of N-acetyl aspartate (NAA) in the visual cortex
    • Resting state functional MRI (RS fMRI) patterns of activity
    • Magnetisation transfer imaging (MTI) derived magnetisation transfer ratio (MTR) of the white and grey matter

  3. Visual Function [ Time Frame: Baseline, 6 and 12 months ]
    • High and low contrast (2.5% and 1.25%) visual acuity.
    • Farnsworth Munsell 100 Hue (FM100) colour vision test.

  4. Visual Electrophysiology [ Time Frame: 0 and 6 months ]
    Differences in visually evoked potential and pattern electro-retinogram between the amiloride and placebo groups as additional measures of visual function

  5. Quality of life questionnaires [ Time Frame: Baseline, 6 and 12 months ]
    • 25 point national institutes for health visual function questionnaire
    • 10 point neuro ophthalmic supplement.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years to 55 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Participants with a first episode of unilateral optic neuritis
  • Participants with an existing diagnosis of relapsing remitting MS and new onset of ON are eligible if they have;

    1. Not had a previous episode of optic neuritis,
    2. A duration of disease of ≤10 years
    3. An EDSS (Expanded Disability Status Scale) of ≤3.
    4. No immune modulating treatment other than β-Interferon or glatiramer acetate at time of recruitment
  • Able to be randomised within 28 days of onset of visual symptoms
  • Visual acuity of ≤6/9
  • Participant is willing and able to give informed consent for participation in the study and able to comply with study visits
  • Male or Female, aged between18 - 55 years.
  • Stable dose of current regular medication for at least 4 weeks prior to study entry.
  • Participant has clinically acceptable urea and electrolytes and estimated glomerular filtration rate (eGFR) >60
  • Able and willing to comply with all study requirements.
  • Willing to allow his or her General Practitioner to be notified of participation in the study.

Exclusion Criteria:

  • Previous diagnosis of optic neuritis
  • Any concomitant immune suppressing or immune modulating therapy excluding β-interferon or glatiramer acetate.
  • Female participants who are pregnant, lactating or planning pregnancy during the course of the study.
  • Concomitant potassium supplements, angiotensin converting enzyme inhibitors, angiotensin II antagonists, cyclosporine, tacrolimus or lithium
  • Any contra-indication to MRI - severe claustrophobia, metal implant, pacemaker, etc.
  • Participant who is terminally ill or is inappropriate for placebo medication
  • Impaired renal function : eGFR ≤60, anuria, acute or chronic renal insufficiency and evidence of diabetic nephropathy
  • Raised serum potassium (K+ >5.5mmol/l)
  • Diabetes
  • Significant concomitant eye disease in either eye that may affect diseased or fellow eye results.
  • Any other significant disease or disorder which, in the opinion of the investigator, may either put the participants at risk because of participation in the study, or may influence the result of the study, or the participant's ability to participate in the study.
  • Participants who have participated in another research study involving an investigational product in the past 12 weeks.

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 identifier (NCT number): NCT01802489

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United Kingdom
John Radcliffe Hospital
Oxford, United Kingdom, OX3 9DU
Sponsors and Collaborators
University of Oxford
Multiple Sclerosis Society of Great Britain and Northern Ireland
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Principal Investigator: Matthew Craner, MBChB PhD University of Oxford
Publications automatically indexed to this study by Identifier (NCT Number):
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Responsible Party: University of Oxford Identifier: NCT01802489    
Other Study ID Numbers: Amiloride 02
First Posted: March 1, 2013    Key Record Dates
Last Update Posted: May 17, 2018
Last Verified: May 2018
Keywords provided by University of Oxford:
Optic neuritis
Multiple sclerosis
Retinal nerve fibre layer
Axonal loss
Optical coherence tomography
Acid Sensing Ion Channels
Additional relevant MeSH terms:
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Multiple Sclerosis
Optic Neuritis
Pathologic Processes
Demyelinating Autoimmune Diseases, CNS
Autoimmune Diseases of the Nervous System
Nervous System Diseases
Demyelinating Diseases
Autoimmune Diseases
Immune System Diseases
Peripheral Nervous System Diseases
Neuromuscular Diseases
Optic Nerve Diseases
Cranial Nerve Diseases
Eye Diseases
Natriuretic Agents
Physiological Effects of Drugs
Acid Sensing Ion Channel Blockers
Sodium Channel Blockers
Membrane Transport Modulators
Molecular Mechanisms of Pharmacological Action
Epithelial Sodium Channel Blockers
Diuretics, Potassium Sparing