In short
Pridopidine hydrochloride is an investigational substance being studied as a potential treatment for amyotrophic lateral sclerosis (ALS). It is a chemically synthesised, orally administered drug that activates the sigma-1 receptor, a protein involved in protecting nerve cells. A Phase 3 trial called PREVAiLS is currently authorised to evaluate whether pridopidine can slow disease progression in 500 participants with ALS.
Key points
- Amyotrophic lateral sclerosis (ALS) is the main condition in the current Phase 3 trial of pridopidine.
- The PREVAiLS trial plans to enrol 500 participants with ALS.
- Pridopidine is given as a 90 mg oral capsule in the trial.
- The trial measures changes in the ALSFRS-R score, a standard scale of daily function in ALS, at weeks 26 and 48.
- Pridopidine is an investigational substance with no marketing authorisation in these records.
- The trial is currently authorised but not yet recruiting.
What is pridopidine?
Pridopidine hydrochloride is a chemically synthesised substance that is still investigational, meaning it has no marketing authorisation in the product records of the trial. It is being developed by Prilenia Therapeutics B.V. and has received orphan designation for amyotrophic lateral sclerosis (ALS), a status given to potential treatments for rare diseases. The product name used in the registry is Pridopidine. Pridopidine has also been investigated in Huntington's disease, a hereditary condition that affects movement and thinking.
How does pridopidine work?
Pridopidine is described as a potent and selective sigma-1 receptor (S1R) agonist. The sigma-1 receptor is a protein found in cells, particularly in the brain and nervous system, that helps cells respond to stress and supports their survival. Activating this receptor is thought to protect nerve cells from damage, which is why pridopidine is being tested in neurodegenerative diseases such as ALS and Huntington's disease.
Which conditions is pridopidine used or studied for?
- Amyotrophic lateral sclerosis (ALS) — a progressive disease of the nervous system that affects nerve cells controlling voluntary muscles. Pridopidine is being tested in a Phase 3 trial to see whether it can slow disease progression.
- Huntington's disease — an inherited condition that causes movement problems, cognitive decline and behavioural changes. Pridopidine has been studied in several trials in this condition, and a new confirmatory study in early Huntington's disease is planned to start in 2026.
How is pridopidine given?
In the PREVAiLS trial, pridopidine is given as a hard capsule for oral use at a dose of 90 mg. The registry also lists a placebo capsule for the comparison arm of the trial.
What do the clinical trials show?
One trial of pridopidine in ALS is registered in the EU Clinical Trials Information System. The trial, called PREVAiLS, is a Phase 3 study that is currently authorised, meaning it has received regulatory approval to proceed but is not yet recruiting. It plans to enrol 500 participants with ALS.
The main measure in the trial is the change in the ALSFRS-R total score, a standard questionnaire that rates a person's ability to perform everyday activities such as walking, speaking, swallowing and breathing. The score is adjusted for mortality, meaning that participants who die during the study are accounted for in the analysis. The trial will assess this score from the start of treatment through week 26 and again through week 48.
What side effects are known?
The provided sources do not contain a detailed list of side effects for pridopidine. The trial itself will collect safety information as part of its design, but no specific side effect data from the PREVAiLS trial are yet available.