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Study on Ambroxol and Clenbuterol for Early Parkinson's Disease in Patients with GBA1 Mutation

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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 Parkinson's disease, a condition that affects movement and can cause tremors, stiffness, and difficulty with balance and coordination. The trial is investigating the effects of a medication called ambroxol, which is being tested for its potential to modify the progression of the disease in patients who have a specific genetic mutation known as the GBA1-mutation. The purpose of the study is to explore whether ambroxol can have a positive impact on the disease's progression in these patients.

Participants in the study will be given either ambroxol or a placebo, which is a substance with no active medication. The study will last for a period of 60 weeks, during which participants will take the medication orally. Throughout the study, various assessments will be conducted to monitor the effects of the treatment. These assessments include evaluating motor skills, which are movements controlled by the brain, and checking for any side effects or adverse events that may occur.

Additional tests will be performed to gather more information about the participants' health and the impact of the treatment. These tests include MRI scans, which use magnetic fields to create detailed images of the brain, and F-DOPA PET scans, which help visualize brain activity. Cognitive assessments, such as the Montreal Cognitive Assessment (MoCA), will also be conducted to evaluate memory and thinking skills. The study aims to provide valuable insights into the potential benefits of ambroxol for individuals with Parkinson's disease and the GBA1-mutation.

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, the participant is required to have a confirmed diagnosis of Parkinson's disease with a GBA1-mutation and a disease duration of less than 10 years.

    The participant must be able to understand the study protocol and perform related actions, including self-administering the medication.

  2. Step 2

    Medication administration

    The participant will receive either ambroxol or a placebo. The medication is taken orally.

    The dosage and frequency of administration will be provided by the study team, and the participant is expected to follow these instructions throughout the trial.

  3. Step 3

    Primary assessment

    The primary assessment involves a comparison of motor skills using the MDS-UPDRS part III motor subscale in an 'OFF' medication state at 60 weeks.

  4. Step 4

    Secondary assessments

    Secondary assessments include safety and tolerability checks through examination of any adverse events.

    Additional tests such as F-DOPA PET, MRI, Montreal Cognitive Assessment (MoCA), Non-Motor Symptoms scale (NMSS), and Parkinson’s Disease Quality of Life questionnaire (PDQ-39) will be conducted.

    Measurement of GCase activity by analyzing sphingolipids in blood cells and plasma is also part of the secondary assessments.

  5. Step 5

    Trial duration

    The trial is expected to conclude by July 1, 2025.

    Participants are required to adhere to the study protocol for the entire duration of the trial.

Who can join the trial?

6 criteria

  • Have a diagnosis of Parkinson's Disease according to specific criteria set by the Movement Disorders Society. This means a doctor has confirmed you have Parkinson's Disease based on certain guidelines.
  • Have a GBA1-mutation. This is a specific change in a gene that is linked to Parkinson's Disease.
  • Have had Parkinson's Disease for less than 10 years at the time of joining the study.
  • Be able to provide written informed consent. This means you understand the study and agree to participate, and you can perform tasks related to the study.
  • Be willing and able to take the study medication, which could be either ambroxol or a placebo, by mouth on your own.
  • Both men and women can participate in the study.

Who cannot join the trial?

5 criteria

  • Patients who do not have **Parkinson's disease** cannot participate. Parkinson's disease is a condition that affects movement and can cause tremors and stiffness.
  • Patients without a **GBA1-mutation** are excluded. A GBA1-mutation is a specific change in a gene that can be related to Parkinson's disease.
  • Patients who are not within the specified age range cannot participate. The age range includes adults and older adults.
  • Both **male and female** patients are eligible, so gender is not a reason for exclusion.
  • Patients who are considered part of a **vulnerable population** are not excluded. A vulnerable population might include groups like children or those unable to give consent, but this study does not exclude them based on vulnerability.
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Investigated drugs

Ambroxol is a medication being studied for its potential to modify the progression of Parkinson's disease in patients who have a specific genetic mutation known as GBA1. It is traditionally used as a treatment for respiratory conditions to help clear mucus, but in this trial, researchers are exploring its effects on the brain and its ability to influence the course of Parkinson's disease.

What is already known about the treatment

Ambroxol – Ambroxol is administered orally in tablet or syrup form. It is currently being studied for its potential benefits in treating Parkinson's disease, particularly in patients with a GBA1 mutation. The main therapeutic indication under investigation is its ability to modify the progression of Parkinson's disease. At the molecular level, Ambroxol is believed to enhance the activity of the enzyme glucocerebrosidase, which may help in reducing the accumulation of certain substances in the brain that are linked to Parkinson's disease. It is classified pharmacologically as a mucolytic agent, traditionally used to clear mucus from the respiratory tract.

Investigated diseases

Parkinson's disease – Parkinson's disease is a progressive neurological disorder that affects movement. It is characterized by tremors, stiffness, and difficulty with balance and coordination. The disease progresses gradually, often starting with barely noticeable tremors in one hand. As it advances, individuals may experience slower movements, muscle stiffness, and impaired posture. Non-motor symptoms such as sleep disturbances, mood changes, and cognitive impairment can also occur. The exact cause is unknown, but it involves the loss of dopamine-producing brain cells.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2024-514976-41-00Protocol codeNL77347.042.22Estimated enrolment80 patientsSponsorUniversitair Medisch Centrum Groningen

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