Otsuka Pharmaceutical Co., Ltd.

June 12, 2020

Otsuka Announces Positive Top-line Results from Two Phase 3 Studies of Centanafadine for the Treatment of Attention-deficit Hyperactivity Disorder (ADHD) in Adult Patients

  • Centanafadine demonstrated statistically significant improvements vs. placebo for primary and key secondary efficacy endpoints in both investigational studies
  • In the combined analysis of tolerability across the two studies, no adverse event was reported by more than 7 percent of patients
  • An estimated 5 percent (11 million) adults in the U.S. are diagnosed with ADHD

Otsuka Pharmaceutical Co., Ltd. and Otsuka Pharmaceutical Development & Commercialization, Inc., a U.S. subsidiary, announce positive top-line results from two, six-week, phase 3 clinical trials that evaluated the efficacy, safety and tolerability of oral centanafadine, a novel investigational compound for the treatment of adult patients with attention-deficit hyperactivity disorder (ADHD*1). The company also plans to investigate the effects of centanafadine in pediatric patients with ADHD, as well as to discuss next steps with the U.S. Food and Drug Administration.

In both trials, 200 mg and 400 mg total, daily oral doses of centanafadine demonstrated statistically significant improvement vs. placebo on the primary efficacy endpoint, change from baseline to Day 42 on the adult ADHD investigator symptom rating scale (AISRS) total score (p < 0.05 in the first study and p < 0.01 in the second study). AISRS is an interview-based evaluation of ADHD symptoms in adult patients, with hyperactive/impulsive and inattention subscales.*2

In both trials, statistically significant improvements versus placebo were also observed in the key secondary efficacy outcome, CGI-S (Clinical Global Impression - Severity scale) change from baseline to Day 42 (p < 0.05).

In a pooled-analysis across the two studies, the most frequently observed side effects for centanafadine (>5 percent and more frequent than placebo) included decreased appetite, headache, nausea, dry mouth, upper respiratory tract infection and diarrhea; no side effect was observed in greater than 7 percent of patients.

About Centanafadine and the Phase 3 Program

Centanafadine is a serotonin-norepinephrine-dopamine, triple-reuptake inhibitor. Approximately, 900 adult patients from age 18 to 55 years old, and diagnosed with ADHD, were randomized in the two phase 3 studies. The studies were randomized, double-blind, multicenter, and placebo-controlled with parallel groups. Patients were randomized 1:1:1 to receive either centanafadine doses of 100 or 200 mg, twice daily (total daily dose of 200 mg or 400 mg, respectively), or placebo twice daily. A long-term safety and tolerability study of centanafadine in a 400 mg total daily dose is ongoing, with top-line results expected in 2021.

About ADHD

According to the Attention Deficit Disorder Association, an estimated 5 percent (11 million) of adults in the U.S. have ADHD, a neuro-behavioral condition that impacts the regulation of a particular set of brain functions and related behaviors. These brain operations include important functions such as attention, concentration, memory, motivation and effort, learning from mistakes, impulsivity, hyperactivity, organization, and social skills. ADHD has no known cure and the majority of people do not outgrow it. Approximately two-thirds or more of children with ADHD continue to have symptoms and challenges in adulthood.

For additional information on ADHD, please visit the National Institute of Mental Health website.


  1. 1
  2. ADHD: The Facts. (n.d.) Retrieved from
  3. 2Spencer TJ, Adler LA, Meihua Qiao, Saylor KE, Brown TE, Holdnack JA, et al. Validation of the adult ADHD investigator symptom rating scale (AISRS). J Atten Disord. 2010;14(1):57-68.