New Orleans, USA – Otsuka Pharmaceutical Development & Commercialisation and Otsuka Pharmaceutical have unveiled promising expanded Phase IIIb results for Simtriyo (centanafadine), a novel therapeutic agent, demonstrating its significant efficacy in treating adults grappling with Attention-Deficit/Hyperactivity Disorder (ADHD) and co-occurring anxiety disorders. The comprehensive data, presented at the prestigious Psych Congress 2026, offers a compelling case for Simtriyo as a valuable addition to the treatment arsenal for a complex patient population often underserved by existing therapies.
The study, a rigorous double-blind, placebo-controlled, and randomized trial, meticulously enrolled 315 adults aged between 18 and 65 years. These participants were diagnosed with generalized anxiety disorder (GAD), social anxiety disorder (SAD), or a combination of both, alongside their ADHD diagnosis. This targeted approach underscores the growing recognition of the intricate interplay between ADHD and anxiety, and the critical need for treatments that can effectively address both.
The findings presented at Psych Congress 2026 represent a significant advancement in understanding Simtriyo’s potential to alleviate the multifaceted symptoms associated with this comorbidity. The data highlights not only improvements in core ADHD symptoms but also a notable impact on anxiety levels, suggesting a synergistic effect that addresses the broader challenges faced by these individuals.
Unveiling Promising Efficacy: Key Findings from the Phase IIIb Trial
At the conclusion of the eight-week treatment period, Simtriyo demonstrated a statistically significant reduction in ADHD symptoms as measured by the Adult ADHD Investigator Symptom Rating Scale (AISRS). The least-squares mean change in AISRS scores was a substantial -18.48 for participants treated with centanafadine, a marked improvement compared to the -12.62 observed in the placebo group. This translates to a treatment difference of -5.87, indicating a clinically meaningful benefit provided by Simtriyo. Crucially, the study reported statistical separation from placebo as early as week 1, suggesting a rapid onset of action.
Beyond the core ADHD symptomology, the study also meticulously evaluated the impact of Simtriyo on anxiety. The Hamilton Anxiety Rating Scale (HAM-A) revealed a statistically significant difference between the treatment and placebo arms. At week 8, centanafadine-treated patients experienced a mean change of -12.55 on the HAM-A, while the placebo group saw a change of -10.63, yielding a treatment difference of -1.92. This finding is particularly significant, as it suggests that Simtriyo may offer a dual benefit, addressing both the inattentive and hyperactive/impulsive symptoms of ADHD alongside the debilitating effects of anxiety.
Further pre-specified analyses delved deeper into the specific domains affected by Simtriyo. The ASRS-18 total score, another key measure of ADHD symptom severity, showed greater improvements with centanafadine. Scores decreased by -23.10 with Simtriyo, compared to -15.80 for placebo, a treatment difference of -7.26. These improvements were observed across critical areas including hyperactivity and impulsivity, inattention, executive function, and emotional dysregulation.
The impact on executive function, a domain often profoundly affected in individuals with ADHD and anxiety, was further illuminated by the Behaviour Rating Inventory of Executive Function-Adult Version (BRIEF-A). The Global Executive Composite showed a change of -17.73 with centanafadine versus -13.46 with placebo, a difference of -4.3. Similarly, the Behavioural Regulation Index demonstrated a change of -14.27 for centanafadine and -10.20 for placebo, with a treatment difference of -4.1. These findings suggest that Simtriyo can positively influence an individual’s ability to plan, organize, self-monitor, and manage their behavior, critical skills for daily functioning.
Both clinician- and patient-reported global assessments corroborated these findings, showing consistent patterns of improvement in ADHD and anxiety severity with centanafadine treatment. The overall safety profile of Simtriyo in this study was found to be generally consistent with previously reported data, a crucial factor for any new therapeutic agent.
A Chronology of Innovation and Development
The journey of Simtriyo to this stage reflects Otsuka’s long-standing commitment to addressing complex central nervous system (CNS) conditions. The company has been at the forefront of developing novel treatments that tackle unmet needs across a spectrum of psychiatric illnesses. The current Phase IIIb results build upon a foundation of prior research and development, culminating in a comprehensive understanding of Simtriyo’s therapeutic potential.
The presentation at Psych Congress 2026 marks a significant milestone in this ongoing development. This annual congress serves as a vital platform for clinicians and researchers to share cutting-edge findings and discuss the latest advancements in psychiatric care. By choosing this venue to unveil these expanded results, Otsuka underscores the clinical significance of their findings and their dedication to engaging with the medical community.
The regulatory landscape for Simtriyo has also seen recent developments. The drug has received approval from the U.S. Food and Drug Administration (FDA) for the treatment of ADHD in adults and pediatric patients aged six and older who weigh at least 20kg. This approval signifies a major step forward, making Simtriyo accessible to a broad patient population. Currently, the drug is undergoing review by the U.S. Drug Enforcement Administration (DEA) for scheduling, a necessary step for all stimulant medications in the United States.
Supporting Data: A Deeper Dive into Efficacy Metrics
The robust statistical analysis underpinning these results provides a clear picture of Simtriyo’s impact. The use of least-squares means in the analysis of the AISRS and HAM-A scores accounts for potential variations and provides a more precise estimate of treatment effects. The early statistical separation from placebo on the AISRS, observed from week 1, is particularly noteworthy. This rapid onset of action can be a significant factor for patients seeking prompt relief from their debilitating symptoms, potentially improving adherence and overall treatment satisfaction.
The ASRS-18, a self-report questionnaire, provides valuable patient perspective on ADHD symptom severity. The substantial difference observed between centanafadine and placebo in this measure further validates the drug’s efficacy from the patient’s viewpoint. The detailed breakdown of improvements across different subscales of the ASRS-18 and the BRIEF-A paints a comprehensive picture of Simtriyo’s multifaceted benefits, extending beyond core ADHD symptoms to encompass crucial aspects of daily functioning.
The inclusion of both clinician- and patient-reported outcomes is a testament to the study’s rigorous design. This dual reporting mechanism provides a more holistic understanding of treatment effectiveness, capturing both objective clinical assessments and subjective patient experiences. The concordance between these different reporting methods strengthens the confidence in the observed efficacy.
Official Responses: Commitment to Addressing Unmet Needs
John Kraus, Executive Vice President and Chief Medical Officer at Otsuka, articulated the company’s strategic vision and commitment to CNS and psychiatric disorders. "At Otsuka, we’re committed to advancing differentiated science that reflects the full complexity of unmet needs across central nervous system conditions and psychiatric illnesses, from ADHD to schizophrenia and beyond," stated Kraus. "The breadth of what we’re presenting at Psych Congress this year reflects our continued commitment across the range of psychiatric conditions."
This statement highlights Otsuka’s dedication to not only developing innovative treatments but also to understanding the intricate and often overlapping nature of psychiatric illnesses. The focus on "differentiated science" suggests a commitment to developing therapies that offer unique mechanisms of action or address specific patient populations with complex needs, such as those with comorbid ADHD and anxiety.
The company’s multifaceted presence at Psych Congress 2026, with presentations covering aripiprazole, centanafadine’s safety and pharmacokinetic profile, human abuse potential, and ulotaront, further underscores their broad engagement with the field of psychiatric research and development. This comprehensive approach demonstrates a commitment to advancing the understanding and treatment of a wide range of mental health conditions.
Implications for Clinical Practice and Future Research
The expanded Phase IIIb results for Simtriyo hold significant implications for clinical practice. For clinicians treating adults with ADHD, the addition of a treatment that also effectively manages co-occurring anxiety disorders is a substantial advancement. This could lead to more streamlined treatment approaches, potentially reducing the need for multiple medications and improving patient adherence and outcomes. The ability of Simtriyo to address both symptom clusters simultaneously offers a more holistic and patient-centered approach to care.
The rapid onset of action observed in the study is also a critical factor, potentially improving patient satisfaction and reducing the time to benefit, which can be crucial for individuals struggling with the daily impact of these conditions. The consistent safety profile further enhances its appeal as a viable treatment option.
Looking ahead, these findings are likely to stimulate further research into the specific mechanisms by which centanafadine exerts its dual therapeutic effects. Understanding how it influences both dopaminergic and noradrenergic pathways, which are implicated in ADHD, and its potential impact on neurotransmitter systems involved in anxiety, could unlock further therapeutic opportunities. Future research may also explore the long-term efficacy and safety of Simtriyo, as well as its effectiveness in different subgroups of patients with ADHD and anxiety.
The success of Simtriyo in this complex patient population also reinforces the importance of recognizing and treating comorbid conditions. As highlighted by Otsuka’s ongoing commitment, the field of psychiatric medicine is moving towards a more integrated and nuanced understanding of mental health, where the interplay of different conditions is acknowledged and addressed comprehensively. The ongoing regulatory review by the DEA will be closely watched as it determines the final accessibility of this promising new treatment option.
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