Efficacy and Safety Study of STX209 (Arbaclofen) for the Treatment of Social Withdrawal in Children With Fragile X Syndrome

A Randomized, Double-Blind, Placebo-Controlled, Fixed-Dose Study of the Efficacy, Safety, and Tolerability of STX209 (Arbaclofen) Administered for the Treatment of Social Function in Children With Fragile X Syndrome

Status

Completed

Phases

Phase 3

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT01325220

Acronym

Harbor-C

Enrollment

172

Registered

2011-03-29

Start date

2011-06-30

Completion date

Unknown

Last updated

2013-07-31

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Fragile X Syndrome

Brief summary

There will be four study periods: Screening (up to 14 days in length), the Treatment Period (8 weeks), the Withdrawal Period (22 days), and Follow-up Period (up to 31 days). Subjects will be randomized to receive either STX209 (5 mg twice daily \[BID\], 10 mg BID or 10 mg three times daily \[TID\]) or placebo. Efficacy,safety and tolerability assessments will be performed periodically

Interventions

DRUGarbaclofen

5 mg bid

DRUGPlacebo

tid

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

TREATMENT

Masking

QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender

ALL

Age

5 Years to 11 Years

Healthy volunteers

Inclusion criteria

* Molecular documentation of the full FMR1 mutation * Current pharmacological treatment regimen has been stable for at least 4 weeks prior to Screening. * Subjects with a history of seizure disorder must currently be receiving treatment with antiepileptics and must have been seizure free for 6 months, or must be seizure free for 3 years if not currently receiving antiepileptics. * If the subject is already receiving stable non-pharmacologic educational, behavioral, and/or dietary interventions, participation in these programs must have been continuous during the 2 months prior to Screening

Exclusion criteria

* Subjects with any condition, including alcohol and drug abuse, which might interfere with the conduct of the study, confound interpretation of the study results, or endanger their own well-being. * Subjects who plan to initiate or change pharmacologic or non-pharmacologic interventions during the course of the study. * Subjects who have taken another investigational drug within the last 30 days. * Subjects who are not able to take oral medications

Design outcomes

Primary

Measure	Time frame	Description
Aberrant Behavior Checklist-Lethargy Social Withdrawal subscale	at 8 weeks of treatment	This is a single subscale of the aberrant behavior checklist entitiled Lethargy Social Withdrawal

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026