Otsuka Pharmaceutical Development & Commercialisation and Otsuka Pharmaceutical have reported expanded Phase IIIb results for Simtriyo (centanafadine) in adults with attention-deficit/hyperactivity disorder (ADHD) and comorbid anxiety disorders.
The results were presented at Psych Congress 2026 in New Orleans, US.
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The double-blind, placebo-controlled, randomised study enrolled 315 adults aged 18–65 with generalised anxiety disorder, social anxiety disorder, or both.
At week 8, the least-squares mean change in the Adult ADHD Investigator Symptom Rating Scale (AISRS) was -18.48 with centanafadine, compared with -12.62 for placebo.
The treatment difference was -5.87, with statistical separation from placebo reported from week 1.
The Hamilton Anxiety Rating Scale (HAM-A) also showed a statistically significant difference at week 8. Scores changed by -12.55 with centanafadine and -10.63 with placebo, giving a treatment difference of -1.92.
Additional pre-specified analyses found greater changes with centanafadine on the ASRS-18 total score, which fell by -23.10 compared with -15.80 for placebo.
The treatment difference was -7.26. Differences were also reported across hyperactivity and impulsivity, inattention, executive function and emotional dyscontrol measures.
On the Behaviour Rating Inventory of Executive Function-Adult Version, the Global Executive Composite changed by -17.73 with centanafadine and -13.46 with placebo, a difference of -4.3.
The Behavioural Regulation Index changed by -14.27 and -10.20, respectively, with a treatment difference of -4.1.
Clinician- and patient-reported global ratings showed similar patterns for ADHD and anxiety severity. The company said the safety profile was generally consistent with previous findings.
The most common treatment-emergent adverse events were nausea, reported in 17.2% of centanafadine recipients versus 5.7% with placebo; decreased appetite, at 13.4% versus 3.2%; and diarrhoea, at 10.2% versus 3.2%.
Simtriyo received US Food and Drug Administration (FDA) approval for ADHD in adults and paediatric patients aged six and over who weigh at least 20kg. It is currently under US Drug Enforcement Administration scheduling review.
Otsuka executive vice-president and chief medical officer John Kraus said: “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.
“The breadth of what we’re presenting at Psych Congress this year reflects our continued commitment across the range of psychiatric conditions.”
Other presentations covered aripiprazole, centanafadine’s safety and pharmacokinetic profile, human abuse potential and ulotaront.
In October 2024, Otsuka Pharmaceutical reported positive interim results from its ongoing Phase III trial evaluating sibeprenlimab, an investigational treatment for adults with immunoglobulin A nephropathy (IgA nephropathy).
