Overview
Tourette syndrome is a neurodevelopmental disorder marked by motor and vocal tics that can wax and wane over time. For many patients, especially children and adolescents, tics can interfere with school, social life, sleep, and emotional well-being. Although several medicines are used to reduce tic severity, current treatment options are often limited by side effects such as sleepiness, weight gain, movement problems, and treatment discontinuation. This phase 3 randomized clinical trial evaluated ecopipam, a selective dopamine D1 receptor antagonist, as a potential new treatment for Tourette syndrome.
Why this study matters
In Tourette syndrome, abnormal dopamine signaling is thought to contribute to tic generation. Most existing medications work by blocking dopamine D2 receptors or by affecting other neurotransmitter systems. Ecopipam is different because it selectively blocks dopamine D1 receptors. This alternative mechanism may offer tic reduction while avoiding some of the adverse effects seen with other drugs.
The trial focused on whether ecopipam could not only improve tic symptoms during an initial open-label treatment period, but also maintain benefit after patients were randomized either to continue the medication or switch to placebo. That design helps determine whether the drug’s effect persists over time and whether stopping it leads to symptom relapse.
Study design
This was a phase 3, double-blind, placebo-controlled randomized withdrawal study conducted from January 31, 2023, to February 4, 2025. Participants were enrolled at 77 sites across 12 countries. Eligible participants were 6 years of age or older and had Tourette syndrome.
The study had two main parts. First, all participants entered a 12-week open-label period in which they received ecopipam. The dose was gradually increased over 3 to 4 weeks to a target of 1.8 mg/kg per day. This gradual titration is important in pediatric and psychiatric trials because it helps improve tolerability and reduces the risk of abrupt side effects.
Participants who responded well, defined as having at least a 25% improvement in the Yale Global Tic Severity Scale Total Tic Score (YGTSS-TTS) at weeks 8 and 12, then entered a second 12-week double-blind period. During this phase, they were randomized to either continue ecopipam or taper to placebo.
The main outcome was time to relapse, defined as losing at least 50% of the tic improvement they had achieved during the open-label period. The primary analysis focused on participants aged 6 to 18 years; adults were analyzed separately as an exploratory group.
Who participated
A total of 216 participants entered the open-label ecopipam period. Most were pediatric participants: 167 were children or adolescents, representing 77.3% of the study population. Overall, 146 participants were male and 70 were female, which is consistent with the known higher prevalence of Tourette syndrome in males.
Among those who responded and were randomized, 43 pediatric participants and 8 adults continued ecopipam, while 47 pediatric participants and 6 adults were switched to placebo. The mean age of randomized pediatric participants was about 14 years.
Effectiveness results
Ecopipam showed a meaningful benefit in pediatric participants. The risk of relapse was significantly lower in those who continued ecopipam compared with those switched to placebo. The hazard ratio was 0.47, with a 95% confidence interval of 0.26 to 0.84, and the result was statistically significant (P = .008). In practical terms, this means that continuing ecopipam reduced the likelihood of tic worsening after initial improvement.
In adults, the direction of the effect was similar, with a hazard ratio of 0.51, but the result was not statistically significant. This likely reflects the very small adult sample size rather than proof of no benefit. Because only 14 adults were included in the randomized phase, the study was not well powered to make a firm conclusion for adults.
Taken together, the findings suggest that ecopipam can maintain clinically meaningful tic improvement in children and adolescents with Tourette syndrome over a 24-week period.
Safety findings
The most frequently reported adverse events with ecopipam, across both the open-label and double-blind periods, were related mainly to the central nervous system. These included somnolence in 11.1% of participants, anxiety in 9.7%, headache in 9.7%, insomnia in 8.8%, tic in 7.9%, and fatigue in 6.5%.
Importantly, ecopipam did not appear to cause clinically meaningful changes in body weight, metabolic measures, or psychiatric scale scores. This is relevant because some current tic medications can lead to substantial weight gain, sedation, or mood-related problems.
No drug-induced movement disorders were observed. That is an encouraging safety signal, since movement-related side effects can be a concern with many dopamine-targeting therapies.
Clinical interpretation
The results support ecopipam as a promising new treatment option for Tourette syndrome, especially in pediatric patients. The study suggests two important points. First, ecopipam can reduce tic severity during active treatment. Second, the benefit appears to persist as long as treatment continues, because relapse was more common when patients were switched to placebo.
The randomized withdrawal design is particularly useful in chronic conditions like Tourette syndrome, where symptoms naturally fluctuate. It helps distinguish true medication benefit from temporary improvement or placebo effects.
For families and clinicians, the findings are meaningful because they address a major gap in Tourette care: the need for an effective medicine that is better tolerated over time. Many patients stop treatment because adverse effects outweigh the benefit. A drug with a different receptor target, and without major weight or metabolic effects, may be especially useful.
What this means for patients and families
Tourette syndrome treatment is often individualized. Some patients benefit from behavioral therapy, especially comprehensive behavioral intervention for tics. Others need medication when tics cause pain, social distress, functional impairment, or difficulty concentrating.
Ecopipam may eventually become another option in this treatment landscape. However, it is important to remember that this was a clinical trial, and treatment decisions should still be made with a clinician who understands the severity of symptoms, age of the patient, comorbid conditions, and risk of side effects.
Families should also know that tic severity can vary from week to week. A medicine may help reduce the overall burden of tics without eliminating them completely. The goal is often meaningful improvement in daily function, not necessarily complete suppression of all tics.
Study limitations
As with all clinical trials, there are limitations. The adult subgroup was small, so the trial could not definitively determine whether adults benefit to the same degree as children. In addition, the randomized phase lasted 12 weeks, which is helpful for understanding short- to medium-term maintenance of effect, but not long-term safety or durability beyond six months.
Another consideration is that participants first had to respond during the open-label period before randomization. This means the second phase studied maintainers of response rather than the entire Tourette syndrome population. That is appropriate for a withdrawal design, but it does not tell us how many nonresponders might benefit from the drug.
Still, the consistency of the findings and the favorable safety profile provide a strong rationale for further evaluation and clinical use where approved or available.
Bottom line
In this phase 3 randomized clinical trial, ecopipam maintained clinically meaningful improvement in Tourette syndrome symptoms and significantly reduced relapse risk in children and adolescents. It was generally well tolerated for up to 24 weeks, with adverse events mainly involving the central nervous system and without notable effects on weight, metabolism, or drug-induced movement disorders.
These results make ecopipam a promising candidate for Tourette syndrome treatment, particularly for pediatric patients who need symptom control but may not tolerate current medications well.
Trial registration
ClinicalTrials.gov Identifier: NCT05615220.