Drug

Arbaclofen

Approved medicine

ClassGABA-B receptor agonistResearchOngoing clinical research

Also known as (R)-4-amino-3-(4-chlorophenyl)butan-oic acid, (R)-Baclofen.

RxNorm1881592 ChEMBLCHEMBL301742UNIINYU6UTW25B

Active clinical trials

Protein targets

Latest activity

beta

Recent clinical, regulatory, research and industry developments relating to this drug.

A Follow-Up Shiftability Study of Arbaclofen With an Open-Label Extension for the Study of Biomarkers in Children and Adolescents With Autism Spectrum Disorders.

Clinical trial2026-06-17Results expected Q4 2026 · ClinicalTrials.gov

A Randomized, Double-Blind, Placebo-Controlled Parallel Group Study to Investigate the Safety and Efficacy of Arbaclofen Extended-Release Tablets for the Treatment of Spasticity in Patients With Multiple Sclerosis (Study OS440-3006)

Clinical trial2025-12-03Results expected Q1 2028 · ClinicalTrials.gov

An Exploratory, Randomized, Double-Blind, Placebo-Controlled and Open-label Extension Study of the Safety, Tolerability, and Efficacy of Arbaclofen in Subjects With 16p11.2 Deletion

Clinical trial2024-12-22Primary completion · ClinicalTrials.gov

A Randomized Placebo-controlled Trial of ARBaclofen vs. Placebo in the Treatment of Children and Adolescents With ASD

Clinical trial2023-08-04Completed · ClinicalTrials.gov

A Phase II Randomized, Double-Blind, Placebo-Controlled Study of the Efficacy, Safety, and Tolerability of Arbaclofen Administered for the Treatment of Social Function in Children and Adolescents With Autism Spectrum Disorders

Clinical trial2023-01-27Completed · ClinicalTrials.gov

An Open-Label Study to Evaluate the Long-Term Safety of Arbaclofen Extended-Release Tablets in Multiple Sclerosis Patients With Spasticity (Study OS440-3005)

Clinical trial2022-08-09Results posted · ClinicalTrials.gov

Clinical trial2022-07-15Results posted · ClinicalTrials.gov

A One Year, Open Label, Dose Escalation Study To Evaluate the Long-Term Safety of Arbaclofen Extended Release Tablets (AERT) in Multiple Sclerosis Subjects With Spasticity

Clinical trial2015-01-01Completed · ClinicalTrials.gov

A Randomized, Double-Blind, Parallel Group Study to Compare the Safety and Efficacy Arbaclofen ER Tablets to Placebo and Baclofen Tablets, USP for the Treatment of Spasticity in Patients With Multiple Sclerosis

Clinical trial2014-04-01Completed · ClinicalTrials.gov

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

Clinical trial2013-07-31Completed · ClinicalTrials.gov

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

Clinical trial2013-07-31Completed · ClinicalTrials.gov

An Open-Label Extension Study to Evaluate the Safety, Tolerability, and Pharmacokinetics in Subject With Fragile X Syndrome

Clinical trial2013-07-01Terminated · ClinicalTrials.gov

Profile

Identifiers & mechanism

Canonical identifiers, marketed brand names and mechanism, resolved across RxNorm, ChEMBL and ATC.

Canonical name

Arbaclofen

Aliases & brands

(R)-4-amino-3-(4-chlorophenyl)butan-oic acid(R)-Baclofen

RxNorm CUI

1881592

ChEMBL ID

CHEMBL301742

UNII

NYU6UTW25B

Primary mechanism

GABA-B receptor agonist

Pharmacology & targets

2 targets

Known molecular targets and mechanisms supported by curated pharmacology databases.

Gamma-aminobutyric acid type B receptor subunit 1

GABBR1 · Q9UBS5

AGONISTGABA-B receptor agonist

Gamma-aminobutyric acid type B receptor subunit 2

GABBR2 · O75899

AGONISTGABA-B receptor agonist

Clinical trials

16 trials

The current development programme across all trial phases — status mix, phase distribution and the late-stage studies shaping the evidence base.

Development programme

CLINICALTRIALS.GOV · LIVE REGISTRY

registered trials across all phases

LATEST COMPLETION 2023

Active studies

Recruiting

Late-stage (III+)

Completed

Discontinued

PHASE DISTRIBUTIONn = 16

Phase 27Phase 39

Late-stage studies

Phase III+ trials still open or recently active — where late-stage evidence is being generated.

Not yet recruitingPH IIIRVL Pharmaceuticals, Inc.n=4422028

A Follow-Up Shiftability Study of Arbaclofen With an Open-Label Extension for the Study of Biomarkers in Children and Adolescents With Autism Spectrum Disorders.

RecruitingPH IIIHospital General Universitario Gregorio Marañonn=1032026

An Open-Label Study to Evaluate the Long-Term Safety of Arbaclofen Extended-Release Tablets in Multiple Sclerosis Patients With Spasticity (Study OS440-3005)

CompletedPH IIIRVL Pharmaceuticals, Inc.n=3232020

CompletedPH IIIRVL Pharmaceuticals, Inc.n=5362019

A One Year, Open Label, Dose Escalation Study To Evaluate the Long-Term Safety of Arbaclofen Extended Release Tablets (AERT) in Multiple Sclerosis Subjects With Spasticity

CompletedPH IIIRVL Pharmaceuticals, Inc.n=1502015

Recent completions

Trials that read out recently, adding to the completed evidence base.

A Randomized Placebo-controlled Trial of ARBaclofen vs. Placebo in the Treatment of Children and Adolescents With ASD

CompletedPH IIHolland Bloorview Kids Rehabilitation Hospitaln=902023

CompletedPH IICelso Arango, MD, PhDn=1242023

An Open-Label Study to Evaluate the Long-Term Safety of Arbaclofen Extended-Release Tablets in Multiple Sclerosis Patients With Spasticity (Study OS440-3005)

CompletedPH IIIRVL Pharmaceuticals, Inc.n=3232020

CompletedPH IIIRVL Pharmaceuticals, Inc.n=5362019

A One Year, Open Label, Dose Escalation Study To Evaluate the Long-Term Safety of Arbaclofen Extended Release Tablets (AERT) in Multiple Sclerosis Subjects With Spasticity

CompletedPH IIIRVL Pharmaceuticals, Inc.n=1502015

CompletedPH IIIRVL Pharmaceuticals, Inc.n=3532014

References & data sources

RxNorm (U.S. National Library of Medicine) — drug identity
ChEMBL (EMBL-EBI) & UniProt — pharmacology and targets
ClinicalTrials.gov — clinical trials