A Trial Evaluating the Long-term Safety and Tolerability of Centanafadine Sustained-release Tablets in Adults With Attention-Deficit/Hyperactivity Disorder

De Novo Participants [De Novo Enrollment has ended 20Sep2019].

Inclusion Criteria:

• De novo participants must meet the Diagnostic and Statistical Manual of MentalDisorders, Fifth Edition (DSM-5) criteria for ADHD (including predominantlyinattentive presentation, hyperactive presentation, or combined presentation) asconfirmed by the Adult ADHD Clinical Diagnostic Scale (ACDS) Version 1.2. To confirmthat ADHD is the primary diagnosis, the Mini International NeuropsychiatricInterview (MINI) will be used to identify and exclude other psychiatric conditionswhich would preclude enrollment.

• Participants are 18 to 55 years of age, inclusive, at the time of consent.

• Participants have BMI of 18 to 40, inclusive

• Participants are willing to discontinue all prohibited psychotropic medicationsstarting from the time of signing the informed consent and up to the 10-day safetyfollow-up period.

Exclusion Criteria:

• Participants has a DSM-5 diagnosis of Other Specified or UnspecifiedAttention-Deficit/Hyperactivity Disorder as confirmed by ACDS Version 1.2.

• Participant has a current comorbid psychiatric disorder that is either controlledwith medications prohibited in this trial or is uncontrolled and associated withsignificant symptoms, including but not limited to: a current major depressiveepisode (per DSM-5 criteria), current symptoms (past 90 days) meeting the DSM-5criteria for a diagnosis of generalized anxiety disorder, obsessive compulsivedisorder, panic disorder, or posttraumatic stress disorder, as established by theMINI. NOTE: Participants with mild mood or anxiety symptoms that do not meetcriteria for diagnosis, who do not require treatment based on the Investigator'sassessment, and do not confound efficacy or safety assessments in the opinion of theexamining Investigator, may be included.

• Participants that have a positive alcohol test (via breathalyzer or blood), apositive drug screen for cocaine, or other illicit drugs (excluding marijuana).Participants with a positive drug screen for confirmed prescription medications atbaseline will not be permitted to continue participation in Trial 405-201-00015.NOTE: Participants that tested positive for marijuana may be permitted to beenrolled if they have no evidence of a substance use disorder, and if they agree torefrain from use for the duration of the trial. Allowance for participants testingpositive for marijuana at screening require explicit approval from the medicalmonitor.

Rollover Participants: Rollover Enrollment has ended 28Aug2020.

Inclusion Criteria:

• Participants who completed the double-blind treatment period and 7-day follow-upafter last dose of investigational medicinal product (IMP) in double-blind trialsand who, in the opinion of the investigator, could potentially benefit fromcentanafadine for ADHD.

Exclusion Criteria:

• Participants who, during the double-blind phase 3 trial experienced, in the opinionof the investigator, poor tolerability to trial medication or whose safetyassessments resulted in new concerns that would suggest the participant may not beappropriate for a 52-week treatment with trial medication.

• Participants who have re-initiated any therapy for adult ADHD during the 7-dayfollow-up period after the final treatment visit of the double-blind phase 3 trial.

• Participants that have a positive alcohol test (via breathalyzer or blood), apositive drug screen for cocaine, or other illicit drugs (excluding marijuana).Participants with a positive drug screen for confirmed prescription medications atbaseline will not be permitted to continue participation in Trial 405-201-00015.NOTE: Participants that test positive for marijuana may not be permitted to rolloverinto the open label study, and must agree to refrain from use for the duration ofthe open label trial. Allowance for participants testing positive for marijuana attime of rollover requires explicit approval from the medical monitor.