NCT04085172

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

A Phase 4, Multicenter, 2-part Study Composed of a Randomized, Double-blind, Parallel-group, Placebo-controlled, Active-comparator, Dose-optimization Evaluation Followed by a 1-Year Open-label Evaluation to Assess the Safety and Efficacy of Guanfacine Hydrochloride Prolonged-release (SPD503) in Children and Adolescents Aged 6 to 17 Years With Attention-deficit/Hyperactivity Disorder

• Status: Completed
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 396 (actual)
• Sponsor: Shire · Industry
• Sex: All
• Age: 6 Years – 17 Years
• Healthy volunteers: Not accepted

Summary

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.

Detailed description

This study will be conducted in two parts Part A and Part B. Part A is a double-blinded, double-dummy, placebo-controlled study with an atomoxetine arm as an active reference to TAK-503. Eligible participants with ADHD will be randomized in a 1:1:1 ratio among TAK-503, atomoxetine, and placebo treatment arms up to 49 weeks of double-blinded treatment. Upon completion of Part A, participants will roll over to Part B directly as per the study protocol directions for an additional 52 weeks of open-label TAK-503 treatment.

Conditions

• Attention Deficit Hyperactivity Disorder

Interventions

Type	Name	Description
DRUG	Guanfacine hydrochloride (TAK-503)	Participants aged 6 to 12 years will receive a dose of 1 to 4 mg and aged 13 to 17 years will receive a dose of 5 to 7 mg TAK-503 oral tablets once daily for 18 weeks in Part A or 52 weeks in Part B.
DRUG	Atomoxetine hydrochloride	Participants will receive Atomoxetine hydrochloride oral capsule once daily for 18 weeks in Part A.
OTHER	Placebo	Participants aged 6 to 12 years will receive a dose of 1 to 4 mg and aged 13 to 17 years will receive a dose of 5 to 7 mg placebo matched to TAK 503 oral tablets once daily for 18 weeks and placebo matched to atomoxetine hydrochloride oral capsules at once daily for 18 weeks in Part A.

Timeline

• Start date: 2019-09-18
• Primary completion: 2025-09-02
• Completion: 2025-09-02
• First posted: 2019-09-11
• Last updated: 2026-04-13
• Results posted: 2026-04-13

Locations

50 sites across 9 countries: United States, Austria, Belgium, Germany, Netherlands, Portugal, Spain, Sweden, United Kingdom

Regulatory

• FDA-regulated drug study