A Study Testing SUL-238 in Patients with Early, Untreated Parkinson’s Disease to Assess Effects on Brain Energy Metabolism

2 1

What is this study about?

This study involves Parkinson’s Disease, a condition that affects movement and occurs when certain nerve cells in the brain gradually break down or die. The treatment being tested is SUL-238, which is given as a film-coated tablet taken by mouth. Some participants will receive SUL-238 while others will receive a placebo, which looks identical to the treatment but does not contain the active substance. The purpose of the study is to assess the effect of SUL-238 on substances in the brain that are related to mitochondria, which are tiny structures inside cells that produce energy.

The study will use a special imaging technique called Magnetic Resonance Spectroscopy, also known as 31P-MRS, to measure certain brain chemicals including ATP, phosphocreatine, and inorganic phosphate in specific areas of the brain such as the putamen, substantia nigra, and motor cortex. These measurements will be taken at the beginning of the study and again after four weeks of treatment to see if there are any changes. The study will also look at changes in certain substances in the blood that are related to mitochondria function.

Participants will be randomly assigned to receive either SUL-238 or placebo, and neither the participants nor the doctors will know which treatment is being given during the study. The study is designed for people who have been recently diagnosed with early Parkinson’s Disease and have not yet received treatment for the condition. Throughout the study, the safety of the treatment will be monitored by checking for any unwanted effects, measuring laboratory values, recording vital signs, performing electrocardiogram tests, and conducting physical and neurological examinations. The treatment period will last for 28 days, with a maximum total dose of 123000 milligrams and a maximum daily dose of 4500 milligrams.

1 Initial assessment and baseline measurements

At the beginning of the study, your current health status will be assessed. This includes a physical examination and a neurological examination to check how your body and nervous system are functioning.

Blood samples will be collected for laboratory tests to check your general health.

Your heart activity will be recorded using an electrocardiogram (a test that measures the electrical activity of your heart).

Your vital signs will be measured, including blood pressure, heart rate, and body temperature.

A specialized brain scan called ³¹P-Magnetic Resonance Spectroscopy will be performed. This scan measures specific chemicals in your brain related to energy production in cells, particularly in areas called the putamen, substantia nigra, and motor cortex.

Blood samples will be taken to measure specific substances in your blood related to how your cells produce energy.

These initial measurements will serve as your baseline, which means they will be used as a reference point to compare changes during the study.

2 Treatment period with study medication

You will be assigned to receive either SUL-238 (the active medication being tested) or a placebo (an inactive substance that looks identical to the active medication but contains no active ingredient).

The study medication comes in the form of film-coated tablets that are taken orally (by mouth).

The assignment to either active medication or placebo will be random, and neither you nor the study staff will know which one you are receiving during the study.

You will take the study medication for a period of 4 weeks.

During this treatment period, your health and any symptoms you experience will be monitored.

3 Week 4 assessment

After completing 4 weeks of treatment, you will undergo the same assessments that were performed at the beginning of the study.

The ³¹P-Magnetic Resonance Spectroscopy brain scan will be repeated to measure any changes in the brain chemicals related to energy production.

Blood samples will be collected again to measure changes in specific substances related to cell energy production.

Your vital signs will be measured again.

A physical examination and neurological examination will be performed.

An electrocardiogram will be recorded to check your heart activity.

Blood samples will be taken for laboratory tests to monitor your general health.

Any side effects or health changes you have experienced during the treatment period will be recorded and assessed.

4 Safety monitoring throughout the study

Throughout the entire study period, any adverse events (unwanted or unexpected symptoms or health problems) will be recorded and monitored.

The study staff will assess the frequency and severity of any adverse events you experience.

Regular checks will be performed to ensure the study medication is not causing any significant changes to your laboratory test results, vital signs, heart activity, or physical condition.

If any concerning changes occur during the study, appropriate medical attention will be provided.

Who Can Join the Study?

You must have Parkinson’s Disease that has not yet been treated with medication, diagnosed according to specific medical criteria. This means you must have bradykinesia, which is slowness of movement, and at least one of the following: stiff muscles, a shaking at rest that occurs 4 to 6 times per second, or problems with balance that are not caused by vision problems, inner ear problems, or problems with sensing where your body is in space.
If you are a woman who can no longer have children, you must have gone through menopause, meaning your last menstrual period was at least 12 months ago and a blood test confirms this, or you must have had surgery to remove your uterus, ovaries, or fallopian tubes, or have had your tubes tied. All women must have a negative pregnancy test before starting the study medication. If you had surgery, you must provide a medical report or ultrasound as proof.
You must have been diagnosed with Parkinson’s Disease no more than 1 year ago.
Your Parkinson’s Disease must be at an early stage, with a score of 1.0 or less on a scale called the Modified Hoehn and Yahr stage, which measures how severe the disease is.
Your score on a test called the Montreal Cognitive Assessment, which checks memory and thinking skills, must be 22 or higher out of 30.
You must be 40 years of age or older.
You must be able to understand what the study involves and sign a consent form before any study procedures begin.
You must be able to complete all tests and evaluations required by the study.
The doctor must believe that you are able to attend all scheduled visits, complete all required tests, and follow the study instructions.
If you are a man or woman who is able to have children, and your partner is also able to have children, you must agree to use very effective birth control methods. Men must continue using birth control for 3 months after the last dose of the study medication. Women must continue using birth control for 6 months after the last dose of the study medication. During this time, men and women must not donate sperm or eggs.

Who Cannot Join the Study?

The study does not list specific reasons why patients cannot participate
General exclusion criteria information is not provided in the available study details
Please note that eligibility for this study will be determined by the research team based on medical history and current health status

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
UMCG	Groningen	The Netherlands

Other Sites

No sites found in this category

Trial status

Country	Status	Recruitment Start
The Netherlands	Recruiting	09.02.2026

Trial locations

SUL-238 is an investigational medication being studied for its potential effects on mitochondria, which are the parts of cells that produce energy. In this trial, researchers want to see if SUL-238 can affect certain energy-related chemicals in the brain of people with early Parkinson’s disease. The medication is being tested to understand whether it might help improve the way brain cells produce and use energy in patients with this condition.

A placebo is also used in this study. A placebo looks like the real medication but contains no active ingredients. It is used to help researchers compare the effects of SUL-238 against no treatment, so they can better understand if the medication is actually working.

Investigated diseases:

Parkinson's disease

Parkinson’s Disease – Parkinson’s Disease is a progressive disorder of the nervous system that affects movement control. The condition develops when certain nerve cells in the brain gradually break down or die, leading to a decrease in dopamine production, a chemical messenger important for coordinating movement. Common signs include trembling of the hands, arms, legs, or face, stiffness of the limbs and trunk, slowness of movement, and problems with balance and coordination. As the disease progresses, these movement difficulties become more pronounced and can interfere with daily activities. People with this condition may also experience changes in speech, writing difficulties, and reduced facial expressions. The symptoms typically begin gradually and worsen over time, affecting one side of the body more than the other initially.

Trial ID:

2025-524674-42-00

Protocol code:

GN-002

Trial Phase:

Therapeutic exploratory (Phase II)

Other Trials to Consider

#1 Clinical Trials Search in Europe

A Study Testing SUL-238 in Patients with Early, Untreated Parkinson’s Disease to Assess Effects on Brain Energy Metabolism

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?