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

Completed · Phase 4 · NCT04085172

Conditions: Attention Deficit Hyperactivity Disorder

Research payments reported, 2025: $121,660
U.S. investigators named: 8
Sites paid: 9
Planned or actual enrollment: 396

About the trial

Sponsor: Shire (with Takeda Development Center Americas, Inc.)
Tested: Guanfacine hydrochloride (TAK-503) (drug), Atomoxetine hydrochloride (drug), Placebo (other)
Dates: Started 2019-09-18; completion 2025-09-02
Results posted: Yes

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.

From ClinicalTrials.gov, last updated 2026-04-13. Full record, eligibility and contacts (opens in a new tab)

Industry funding

Takeda Pharmaceuticals U.S.A., Inc. reported $121,660 in research payments for this study in 2025 (87 payments).

Research payments usually go to hospitals, universities and research sites to run a study, not to the investigators personally. A payment is not evidence of wrongdoing.

U.S. investigators named on this study

Clinicians the company named as principal investigators in its Open Payments reports.

Sources: CMS Open Payments research payments (program year 2025) and ClinicalTrials.gov, U.S. National Library of Medicine.

At a glance

About the trial

Industry funding

U.S. investigators named on this study

Sites paid to run it