Repurposed Liver Drug UDCA Enters Global Multi-Arm Trial to Halt Parkinson's Progression

The fastest route to a disease-modifying Parkinson's treatment requires a drug that has already cleared decades of human safety testing. A medication prescribed for more than 30 years to treat liver disease meets that exact constraint, and has now officially joined the world's largest clinical trial dedicated to halting the progression of Parkinson's disease.[1][2][3]

The Edmond J. Safra Accelerating Clinical Trials in Parkinson's Disease (EJS ACT-PD) platform operates as a multi-stage initiative that tests several repurposed drugs simultaneously against a shared placebo group. This structure allows researchers to identify effective compounds much faster than traditional, single-drug clinical trials.[2][3]

Ursodeoxycholic acid (UDCA) becomes the third active treatment arm in the EJS ACT-PD trial. It joins two other repurposed medications that entered the study when it launched in 2025: telmisartan, a drug typically used to lower blood pressure, and terazosin, a treatment for enlarged prostates.[2][3]

The trial is currently active at 26 National Health Service (NHS) sites across the United Kingdom, with plans to expand to 40 hospital locations. So far, more than 189 participants have been randomized into the study, out of an initial target enrollment of 2,000 patients.[2][5]

"This is an excellent example of how discoveries made in patient-derived tissue can progress through early clinical testing towards large-scale trials," said Professor Oliver Bandmann, a researcher at the University of Sheffield. "The ultimate aim is developing treatments that slow or stop the progression of Parkinson's disease."[1][5]

Targeting Cellular Power Plants

The inclusion of UDCA stems from extensive preclinical work conducted by researchers at the University of Sheffield and the Sheffield Teaching Hospitals NHS Foundation Trust. The scientific team systematically screened an entire library of existing compounds using tissue samples derived directly from Parkinson's patients.[1][5]

That screening process identified UDCA as a highly promising candidate for protecting dopamine-producing nerve cells. The drug appears to work by improving the function of mitochondria, the microscopic structures responsible for generating energy within cells, which often malfunction in patients with Parkinson's disease.[1][5]

When mitochondrial function declines, nerve cells in the movement-controlling areas of the brain begin to fail and eventually die. By restoring these cellular power plants, researchers believe UDCA can prevent this cellular malfunction and fundamentally alter the trajectory of the relentlessly progressive condition.[1][5]

Because UDCA is already an established therapy for certain liver conditions, its safety profile and potential side effects are well documented. This existing medical knowledge allowed researchers to bypass years of preliminary safety testing that a completely novel chemical compound would require.[2][3]

The drug was selected for the EJS ACT-PD trial following a rigorous review of hundreds of potential therapies by a panel of scientific experts and patient advocates. The committee specifically targeted compounds that demonstrated the strongest biological evidence for modifying the disease process.[2][5]

Building on Early Clinical Success

The decision to advance UDCA into a large-scale trial builds directly on the results of a phase 2 proof-of-concept study published in 2023. Known as the UP study, that initial trial involved 30 participants with Parkinson's disease and was designed primarily to confirm that high doses of the liver drug were safe.[3][5]

Brain imaging conducted during the UP study confirmed that UDCA was successfully reaching the substantia nigra, the specific brain region most affected by Parkinson's disease. The scans also indicated that the drug was having the intended effect on mitochondrial function within those targeted tissues.[3]

While the phase 2 trial did not show a statistically significant improvement in movement symptoms when measured by the traditional MDS-UPDRS clinical assessment scale, it yielded other encouraging clinical signals. Participants taking UDCA demonstrated measurable improvements in their gait and walking ability when evaluated using objective wearable motion sensors.[3]

The new EJS ACT-PD trial will test UDCA at a substantial dosage, ranging from 1,500 to 2,500 milligrams per day depending on the participant's body weight. Because of this high daily volume, patients assigned to the UDCA arm will take between three and five tablets split across three separate doses each day.[2]

To maintain the integrity of the blinded trial, researchers have introduced a matched placebo regimen specifically for the UDCA group. Participants will not know whether they are receiving the active liver medication, one of the other two repurposed drugs, or a dummy pill.[2]

A Collaborative Funding Model

The EJS ACT-PD platform represents a massive collaborative effort across the medical research community, led nationally by University College London and Newcastle University. The initiative is sponsored by UCL and relies on a broad coalition of public and philanthropic financial support.[1][2]

Primary funding comes from the Efficacy and Mechanism Evaluation Programme, which operates as a partnership between the Medical Research Council and the National Institute for Health and Care Research. Additional financial backing is provided by major advocacy organizations including Parkinson's UK and The Michael J. Fox Foundation.[1][5]

The trial has generated immense interest within the patient community, highlighting the urgent demand for disease-modifying therapies. According to trial organizers, more than 2,120 individuals have already registered their interest in participating in the study as it expands across the country.[2]

Currently, all available treatments for Parkinson's disease focus entirely on managing symptoms, such as tremors, stiffness, and slow movement. While these medications can significantly improve a patient's quality of life, they do nothing to stop the underlying death of dopamine-producing brain cells.[3][5]

If UDCA or either of the other repurposed drugs proves effective in the EJS ACT-PD trial, it would mark a historic breakthrough in neurology. A successful outcome would deliver the first therapy capable of fundamentally altering the biological course of Parkinson's disease.[3][5]

The Promise of Drug Repurposing

The strategy of repurposing existing medications has gained significant traction in neurological research in recent years. By starting with drugs that have already cleared initial regulatory hurdles for other conditions, scientists can dramatically reduce the time and cost associated with bringing a new treatment to market.[3]

This approach is particularly vital for complex, slow-moving neurodegenerative conditions like Parkinson's disease, where traditional drug development can take decades and cost billions of dollars. The multi-arm design of the EJS ACT-PD trial amplifies these efficiencies by testing several candidates simultaneously.[2][3]

Researchers emphasize that the addition of UDCA as the third treatment arm does not imply it is expected to be more effective than telmisartan or terazosin. All three medications met the same rigorous evidentiary standards required for inclusion in the platform.[2]

The trial's adaptive design allows the research team to continuously monitor the performance of each drug at predetermined intervals. If a specific treatment arm fails to show sufficient promise, it can be dropped from the study and replaced with a new candidate without halting the entire trial.[2]

"Repurposing drugs can help us to accelerate the search for new treatments to manage Parkinson's symptoms, and even slow or stop the condition," noted Parkinson's UK in a statement regarding the trial's expansion. The organization funded the initial laboratory screening that first identified UDCA's potential.[3]

Next Steps for Participants

Patients newly enrolling in the EJS ACT-PD trial will undergo a series of initial screening tests to determine their medical eligibility. Based on those results, they will be randomly assigned to one of the active treatment groups or a corresponding placebo arm that is safe for their specific health profile.[2]

The most common side effects associated with UDCA include mild nausea and diarrhea, which typically resolve within a few days of starting the medication. Because the drug has been used safely in liver patients for decades, clinicians are well-equipped to manage these minor adverse reactions.[2]

The trial will track participants over an extended period to measure changes in their disease progression, utilizing both traditional clinical assessments and advanced objective monitoring tools. This comprehensive data collection will provide a definitive answer regarding UDCA's efficacy in the brain.[2][3]

As the study continues to expand across the UK's National Health Service network, researchers remain focused on their ultimate goal. The successful identification of a disease-modifying therapy would transform a diagnosis of Parkinson's disease from a relentlessly progressive condition into a manageable, chronic state.[1][5]