A Study of TAK-503 in Children and Teenagers With Attention Deficit Hyperactivity Disorder (ADHD)

Completed · Phase 4 · Has a placebo group

Conditions studied: Attention Deficit Hyperactivity Disorder

In brief

The main aim of this study is learn more about long-term TAK-503 treatment in children and teenagers with ADHD for whom earlier stimulant treatment did not work. The study has two parts (A and B). In Part A, participants will take tablets of TAK-503, atomoxetine or placebo and in Part B TAK-503 tablets.

Key facts

Study ID

NCT04085172

Run by

Shire

People needed

396

Starts

2019-09-18

Expected to finish

2025-09-02

Last updated by the study team

2026-04-13

Who can join

Age: 6 and older, up to 17. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• Study Part A:
• Participant is a male or female aged 6 to 17 years inclusive at the time of consent/assent.
• Participant must meet Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for a primary diagnosis of ADHD based on a detailed psychiatric evaluation using the Kiddie-Schedule for Affective Disorders-Present and Lifetime Version (K-SADS-PL) by a trained child and adolescent psychiatrist at screening (Visit 1A).
• Participant for whom prior stimulant therapy is not suitable, not tolerated, or shown to be ineffective as determined by investigator clinical assessment and review of the Prior Stimulant Medication Questionnaire (PSMQ) administered during screening (Visit 1A).
• Participant has an ADHD-RS-5 total score greater than or equal to (> =) 28 at baseline (Visit 2A).
• Participant has a baseline (Visit 2A) CGI-S score > = 4.
• Participant who is a female of childbearing potential (FOCP) and postmenarchal must have a negative serum beta-human chorionic gonadotropin (β-hCG) pregnancy test at screening (Visit 1A) and a negative urine pregnancy test at baseline (Visit 2A), be nonlactating, and agree to comply with any applicable contraceptive requirements described in the protocol. Female of child bearing potential is defined as any female participant who is at least aged 9 years or younger than 9 years and postmenarchal.
• Participants parent or legally authorized representative (LAR) must provide signature of informed consent. Documentation of assent (if applicable) must be provided by the participant indicating that the participant is aware of the investigational nature of the study and the required procedures and restrictions in accordance with the International Council for Harmonisation (ICH) Good Clinical Practice (GCP) Guideline E6[R2] and applicable regulations, before completing any study-related procedures.
• Participant and parent/LAR are willing and able to comply with all the testing and requirements defined in this protocol, including oversight of morning dosing. Specifically, the parent/LAR must be available for the duration of the study to administer the investigational medicinal product (IMP) dose each morning when the participant awakens.
• Participant has supine and standing blood pressure (BP) measurements less than the 95th percentile for age, sex, and height at both screening (Visit 1A) and baseline (Visit 2A).
• Participant is functioning at an age-appropriate level intellectually, as judged by the investigator.
• Participant is able to swallow intact tablets and capsules.
• Study Part B:
• Female participants of child-bearing potential must have a negative serum β-hCG pregnancy test if a screening visit is conducted and/or a negative urine pregnancy test at baseline and agree to comply with any applicable contraceptive requirements of the protocol. An FOCP is defined as any female participant who is at least aged 9 years or younger than 9 years and postmenarchal.
• Participant has a supine and standing BP measurement less than the 95th percentile for age, sex, and height.

You may not qualify if…

• Study Part A:
• Participant has a current, controlled (requiring medication or therapy) or uncontrolled, comorbid psychiatric disorder (except oppositional defiant disorder), including but not limited to any of the following comorbid Axis I and Axis II disorders (the K-SADS-PL should be reviewed to confirm diagnosis, if necessary):
• Post-traumatic stress disorder (PTSD)
• Bipolar illness, psychosis, or family history in either biological parent
• Pervasive developmental disorder
• Obsessive-compulsive disorder (OCD)
• Psychosis/schizophrenia
• Serious tic disorder or a family history of Tourette's disorder
• Participant is currently considered to be a suicide risk by the investigator; has made a previous suicide attempt; has a history of, or currently demonstrating, active suicidal ideation.
• Participant has a substance abuse disorder as defined by DSM-5 criteria or has been suspected of a substance abuse or dependence disorder (except nicotine) within the past 6 months.
• Participant has a clinically important abnormality on the urine drug and alcohol screen (except for the participants current ADHD stimulant, if applicable) at screening (Visit 1A).
• Participant has been physically, sexually, and/or emotionally abused.
• Participant has any other disorder that as judged by the investigator could contraindicate TAK-503 or confound the results of the safety and efficacy assessments.
• Participant has any condition or illness including any clinically significant abnormal laboratory value at screening (Visit 1A) or, if the laboratory test was repeated, at baseline (Visit 2A) that, as judged by the investigator, would be an inappropriate risk to the participant and/or could confound the interpretation of study results.
• Participant has current abnormal thyroid function, defined as abnormal thyroid-stimulating hormone and thyroxine at screening (Visit 1A). Treatment with a stable dose of thyroid medication for > = 3 months before screening will be permitted.
• Participant has a known history or presence of: malignancy (except nonmelanoma skin cancer), pregnancy, and/or a developmental delay or abnormality associated with growth or sexual maturation delays that are not related to ADHD.
• Children aged 6 to 12 years with a body weight less than (<) 25.0 kg or adolescents aged > = 13 years with a body weight < 34.0 kg at screening (Visit 1A) or baseline (Visit 2A).
• Participant is significantly overweight based on the Centers for Disease Control (CDC) BMI-for-age sex-specific charts at screening (Visit 1A) or baseline (Visit 2A). For this study, significantly overweight will be defined as a BMI that is greater than the 95th percentile.
• Participant has a known history or presence of: structural cardiac abnormalities, serious heart rhythm abnormalities, syncope, cardiac conduction problems (e.g. clinically significant heart block or QT interval prolongation), bradycardia, or exercise-related cardiac events including syncope and presyncope.
• Participant has clinically significant electrocardiogram (ECG) findings, as judged by the investigator, at baseline (Visit 2A).
• Participant has orthostatic hypotension* or a known history of hypertension. (*Orthostatic hypotension is defined as a sustained reduction of systolic blood pressure of at least 20 millimeter of mercury (mm Hg) or diastolic blood pressure of 10 mm Hg within 3 minutes of standing from supine.)
• Participant has a known family history of sudden cardiac death or ventricular arrhythmia.
• Participant is currently using any medication that violates protocol-specified washout criteria at baseline (Visit 2A), including any ADHD medication or other prohibited medications such as herbal supplements, medications that affect BP or heart rate (HR) or medications that have central nervous system (CNS) effects or affect cognitive performance, such as sedating antihistamines and decongestant sympathomimetics (inhaled bronchodilators are permitted) or a history of chronic use of sedating medications (i.e., antihistamines).
• Participant has a medical condition except ADHD that requires treatment with any medication that affects the CNS.
• Participant is female and pregnant or currently lactating.

Where it is running

• Harmonex Neuroscience Research — Dothan, Alabama, United States
• Advanced Research Center, Inc. — Anaheim, California, United States
• Sun Valley Research Center, Inc. — Imperial, California, United States
• Alliance Research — Long Beach, California, United States
• PCSD Feighner Research — San Diego, California, United States
• Homestead Medical Research — Homestead, Florida, United States
• Clinical Neuroscience Solutions, Inc. — Jacksonville, Florida, United States
• Care Research Center, Inc. — Miami, Florida, United States
• Clinical Neuroscience Solutions, Inc. — Orlando, Florida, United States
• AMR Conventions Research, Ltd — Naperville, Illinois, United States
• Collective Medical Research LLC — Prairie Village, Kansas, United States
• Qualmedica Research, LLC — Bowling Green, Kentucky, United States
• Qualmedica Research, LLC — Owensboro, Kentucky, United States
• Alivation Research, LLC — Lincoln, Nebraska, United States
• Center for Psychiatry and Behavioral Medicine, Inc. — Las Vegas, Nevada, United States
• University of Cincinnati — Cincinnati, Ohio, United States
• Cutting Edge Research Group — Oklahoma City, Oklahoma, United States
• Clinical Neuroscience Solutions, Inc. — Memphis, Tennessee, United States
• Family Psychiatry of The Woodlands — The Woodlands, Texas, United States
• Clinical Research Partners, LLC — Petersburg, Virginia, United States
• LKH-Klinikum Graz — Graz, Austria
• Medizinische Universtität Wien — Vienna, Austria
• UZ Brussel — Brussels, Belgium
• UPC KU Leuven Afdeling Kinderpsychiatrie ADHD-raadpleging — Leuven, Belgium
• Foyer Saint Francois — Namur, Belgium

Full record on ClinicalTrials.gov

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