Open-label Safety Study of Dipraglurant (ADX48621) in Patients With Parkinson's Disease Receiving Levodopa-based Therapy

An Open-label Safety Study of Dipraglurant (ADX48621) in Patients With Parkinson's Disease Receiving Levodopa-based Therapy With or Without Concomitant Dopaminergic Medications

This open-label study is designed to assess the long-term safety and tolerability of dipraglurant in PD patients for up to 52 weeks (at doses of 150-300 mg per day) for patients that have completed an Addex sponsored double-blind clinical trial of dipraglurant.

Study Overview

• Status: Terminated
• Conditions: Parkinson Disease; Dyskinesias; Dyskinesia, Drug-Induced
• Intervention / Treatment: Drug: Dipraglurant

• Study Type: Interventional
• Enrollment (Actual): 17
• Phase: Phase 2; Phase 3

Contacts and Locations

Study Locations

• United States
  • Georgia
    • Augusta, Georgia, United States, 30912
      • Augusta University
  • Kansas
    • Kansas City, Kansas, United States, 66160
      • University of Kansas Medical Center
  • New Jersey
    • New Brunswick, New Jersey, United States, 08901
      • Rutgers, The State University of New Jersey
  • New York
    • New York, New York, United States, 10029
      • Icahn School of Medicine at Mount Sinai
  • Ohio
    • Columbus, Ohio, United States, 43210-1267
      • The Ohio State University Wexner Medical Center
  • Pennsylvania
    • Abington, Pennsylvania, United States, 19001-3816
      • Abington Neurologic Associates
    • Philadelphia, Pennsylvania, United States, 19107
      • University of Pennsylvania

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 30 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Completed an Addex randomized controlled study of dipraglurant and, in the judgement of the Investigator, may benefit from open-label treatment
• Able to take study drug 3 times daily and no less than 3 hours apart
• Must be taking levodopa not less than 3 times daily throughout the study
• Must maintain stable regimen of antiparkinson's medications (including levodopa) and be willing to continue the same doses and regimens for the first 4 weeks of the study

Exclusion Criteria:

• Patient is judged by the Investigator to be inappropriate for the study (for reasons such as, but not limited to, significant noncompliance in the Addex randomized controlled study of dipraglurant)
• Use of amantadine or amantadine ER throughout the study
• Use of memantine throughout the study
• Any use of marijuana or other cannabis/cannabinoid products for the first 4 weeks of study participation

Other protocol-defined inclusion and exclusion criteria may apply

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dipraglurant TID	Drug: Dipraglurant; Oral 50 mg and 100 mg tablet; Other Names: ADX48621

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Long-term safety and tolerability of dipraglurant as measured by incidence of adverse events	Testing the safety and tolerability of dipraglurant in patients with Parkinson's Disease Levodopa-induced dyskinesia based on the incidence of adverse events reported by patients and/or as identified by the Investigator based on clinical assessments conducted during the study.	Baseline (Day 1) to Week 52

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Evaluate the continued utility of dipraglurant on dyskinesia as assessed by a change-from-baseline score on the Movement Disorder Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS).	The MDS-UPDRS is a Parkinson's Disease (PD) rating scale scored from 0-272; it evaluates progression of disease in patients with PD. A higher score indicates more severe PD.	Baseline (Day 1) to Week 52

Collaborators and Investigators

• Sponsor: Addex Pharma S.A.

Study record dates

Study Major Dates

• Study Start (Actual): October 25, 2021
• Primary Completion (Actual): June 17, 2022
• Study Completion (Actual): August 15, 2022

Study Registration Dates

• First Submitted: November 1, 2021
• First Submitted That Met QC Criteria: November 1, 2021
• First Posted (Actual): November 11, 2021

Study Record Updates

• Last Update Posted (Actual): August 6, 2025
• Last Update Submitted That Met QC Criteria: August 1, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: Parkinson's disease; Dyskinesia; Levodopa-induced Dyskinesia
• Additional Relevant MeSH Terms: Synucleinopathies; Neurologic Manifestations; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Neurodegenerative Diseases; Chemically-Induced Disorders; Movement Disorders; Drug-Related Side Effects and Adverse Reactions; Poisoning; Parkinsonian Disorders; Basal Ganglia Diseases; Neurotoxicity Syndromes; Dyskinesias; Parkinson Disease; Dyskinesia, Drug-Induced
• Other Study ID Numbers: ADX48621-302

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No