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Levodopa

Clinical trials investigating Levodopa are studying how it is used in Parkinson’s disease and other patient groups. These trials look at outcomes such as motor symptoms, “ON” time, safety, and patient-reported results. The studies include people with Parkinson’s disease, advanced disease with motor fluctuations, healthy adults, and a small rare-disease group.

Table of Contents

Clinical trials overview

These studies investigate Levodopa in different trial settings, mostly for Parkinson’s disease and related movement problems.[1] The trial data includes studies that are authorised, one that is completed, and designs that range from early testing to larger comparative studies.[1]

Some trials study Levodopa directly, while others study Levodopa-based treatment strategies, devices, or comparison regimens in people with Parkinson’s disease.[1] The main goal across the studies is to understand effectiveness, safety, tolerability, and how treatment affects daily movement control.[1]

Who is being studied

Most trials include people with Parkinson’s disease, including early to moderate disease, advanced disease, and motor fluctuations.[1] Motor fluctuations means symptoms can change during the day, with “good” and “bad” movement periods.[1]

One trial includes healthy adult volunteers, and its purpose is to compare inhaled Levodopa products in a non-patient setting.[1] Another small Phase 2 study includes patients with a rare CTNNB1-related neurodevelopmental disorder, which means a developmental condition linked to a specific gene change.[1]

Trial phases and study designs

The trial set includes Phase 1, Phase 2, Phase 3, and Phase 3b studies.[1] Phase 1 in this group is a bioavailability study in healthy adults, while later phases focus more on symptom control, safety, and patient experience.[1]

Most of the studies are interventional, which means the researchers assign a treatment and then measure the results.[1] Some are randomized, placebo-controlled, or open-label, meaning either the treatment is compared fairly with another option or both the researchers and participants know what is given.[1]

Main outcomes being measured

A common outcome is motor symptom change, often measured with MDS-UPDRS Part 3, a standard scale for movement problems in Parkinson’s disease.[1] One Phase 2 study measures this at several follow-up visits and looks at change from baseline to month 18.[1]

Several studies measure ON time, which is the time when movement symptoms are better controlled during the day.[1] One Phase 3 study focuses on ON time without troublesome dyskinesia, while another compares good ON time at Week 12 between treatment groups.[1]

Safety and tolerability are also important outcomes, especially in the long-term infusion study and in the Phase 1 bioavailability trial.[1] The healthy adult study also measures pharmacokinetic endpoints, which are body-level measurements such as peak concentration and total exposure to the drug.[1]

One small rare-disease study measures motor function with the GMFM-88, a 88-item test used to track gross motor skills before and after treatment.[1] Another study uses a patient questionnaire to evaluate a new medicine dispenser and app for Flexilev minitablets.[1]

Key trial examples

The MONTPARK trial is a Phase 2 randomized placebo-controlled study in mild to moderate Parkinson’s disease, and it measures motor symptoms with MDS-UPDRS Part 3 over time.[1] Its main objective is to examine disease progression in early to moderate Parkinson’s disease.[1]

The BouNDless study is a Phase 3 trial in Parkinson’s disease with motor fluctuations, and it compares continuous subcutaneous ND0612 with oral treatment using diary-based ON/OFF recordings.[1] Its primary endpoint is daily ON time without troublesome dyskinesia, adjusted to waking hours.[1]

The study titled “Management of Parkinson’s disease if levodopa is broken down prematurely” is a Phase 2 trial in Parkinson’s disease that looks at response rates and compares apomorphine versus Levodopa, and rifaximin versus placebo.[1] It is aimed at people with increased activity of Levodopa-metabolizing enzymes or bacteria that produce related enzymes.[1]

The CTNNB1 pilot study is a very small Phase 2 trial with only seven participants, and it measures motor score change from day 1 to 6 months using the GMFM-88.[1] This makes it a focused exploratory study in a rare patient group.[1]

The BeyoND study is a Phase 2 long-term safety trial of continuous subcutaneous ND0612 in advanced Parkinson’s disease, and its main goal is to assess systemic and local safety and tolerability over 12 months.[1] This kind of study helps show how a treatment performs over a longer period.[1]

The INITIATE-LECIG trial is a Phase 3 study in Parkinson’s disease that compares LECIG therapy with best medical treatment for hyperdopaminergic symptoms on the Ardouin Behavioural Scale.[1] Hyperdopaminergic symptoms means symptoms linked to too much dopamine-related stimulation, as defined by the study scale.[1]

The ADIP study is a Phase 3b open-label randomized trial in advanced Parkinson’s disease with motor fluctuations, and it compares IPX203 with immediate-release Levodopa and a decarboxylase inhibitor regimen.[1] Its primary endpoint is the change in good ON time at Week 12.[1]

The OraFID study is a Phase 3 patient evaluation of a new medicine dispenser and app for Flexilev minitablets, and the main outcome is a self-reported questionnaire about the device.[1] This shows that some trials focus not only on medicine effects but also on how easy treatment is to use in daily life.[1]

The completed Phase 1 Levodopa Cyclops™ study in healthy adults compared inhaled Levodopa Cyclops™ with INBRIJA® and measured pharmacokinetic endpoints such as Cmax, Tmax, AUC, and half-life.[1] It was designed to find the dose at which comparative bioavailability would be reached.[1]

What these studies may mean for patients

For patients, these trials show that Levodopa-related research is not limited to one question.[1] The studies look at symptom control, daily function, long-term safety, treatment delivery, and whether new approaches can improve “good time” during the day.[1]

Some studies are small and early, while others are larger and designed to compare treatments in a more practical way.[1] Together, they help researchers understand where Levodopa-based treatment strategies may fit for different patient groups, especially people living with Parkinson’s disease.[1]

Trial ID Phase Condition studied Status Enrollment
2023-504278-39-00 Phase 2 Parkinson’s disease Authorised 98
NCT04006210 Phase 3 Parkinson’s disease Authorised 381
2024-510629-24-00 Phase 2 Parkinson’s disease Authorised 81
2024-514852-34-01 Phase 2 Neurodevelopmental disorders, rare disease, CTNNB1 Authorised 7
NCT02726386 Phase 2 Parkinson’s disease Authorised 214
2025-521048-39-00 Phase 3 Parkinson Disease Authorised 150
2025-521772-57-00 Phase 3 Motor fluctuations in advanced Parkinson’s disease Authorised 91
2025-524296-23-01 Phase 3 Parkinsons Disease Authorised 58
2023-504687-42-00 Phase 1 Healthy adult subjects Completed 26

FAQ

  • What is being studied in Levodopa clinical trials? The trials study different ways to use Levodopa in Parkinson’s disease and related settings. They measure symptom control, time spent in a good movement state, safety, tolerability, and how well patients can use a device or treatment plan.
  • Who can take part in these studies? Most trials include people with Parkinson’s disease, including early to moderate disease, advanced disease, or motor fluctuations. One trial includes healthy adult volunteers, and one small study includes patients with a CTNNB1-related neurodevelopmental disorder.
  • What trial phases are shown for Levodopa studies? The trials range from Phase 1 to Phase 3b. Phase 1 focuses on bioavailability, which means how much of the drug reaches the body, while later phases study effectiveness, safety, and daily symptom control.
  • What outcomes do these trials measure? Common outcomes include motor scores such as MDS-UPDRS Part 3, daily “ON” time without troublesome dyskinesia, safety and tolerability, and patient questionnaires. Some studies also measure bioavailability using pharmacokinetic endpoints like Cmax and AUC.
  • Are these trials only for Parkinson’s disease? Most of them are for Parkinson’s disease, but not all. One trial studies Levodopa in a rare neurodevelopmental disorder linked to CTNNB1, and one Phase 1 study was done in healthy adults for comparison of inhaled Levodopa products.

Ongoing Clinical Trials on Levodopa

  • Study of IPX203 compared to levodopa/carbidopa in patients with advanced Parkinson’s disease and motor fluctuations

    Recruiting

    1 1 1 1
    Investigated diseases:
    Investigated drugs:
    Italy Poland Spain

  • Study of levodopa and carbidopa treatment for patients with neurodevelopmental disorder caused by CTNNB1 gene mutation

    Recruiting

    1 1
    Investigated diseases:
    Investigated drugs:
    France

  • Study of intestinal gel containing levodopa, carbidopa and entacapone to treat motor and behavioral symptoms in patients with Parkinson’s disease

    Recruiting

    1 1 1 1
    Investigated diseases:
    Investigated drugs:
    Germany

  • Study of apomorphine and rifaximin for Parkinson’s disease patients with reduced levodopa effectiveness

    Recruiting

    1 1
    Investigated diseases:
    Investigated drugs:
    The Netherlands

  • Study on Montelukast for Slowing Parkinson’s Disease Progression in Patients with Mild to Moderate Symptoms

    Recruiting

    1 1
    Investigated diseases:
    Investigated drugs:
    Sweden

  • An observational study of carbidopa and levodopa use with a new dispensing device and app in patients with Parkinson’s disease

    Not yet recruiting

    1 1 1 1
    Investigated drugs:
    Sweden

  • Study on the Effectiveness and Safety of ND0612 Infusion vs. Oral Treatment for Parkinson’s Disease Patients with Motor Fluctuations

    Not recruiting

    1 1
    Investigated diseases:
    Investigated drugs:
    Austria Belgium Czechia France Italy Poland +3

  • Study on the Long-Term Safety of ND0612 (Carbidopa, Levodopa) Infusion for Patients with Advanced Parkinson’s Disease

    Not recruiting

    1 1
    Investigated diseases:
    Investigated drugs:
    Austria France Italy Poland

Glossary

  • Parkinson’s disease: A brain condition that can cause slowness, stiffness, shaking, and movement problems. Most of the trials in this group study people with this condition.
  • Motor symptoms: Problems with movement, such as stiffness, slowness, or shaking. Several trials measure whether these symptoms improve over time.
  • MDS-UPDRS Part 3: A doctor-rated scale used to measure movement problems in Parkinson’s disease. It is often used as an outcome in trials.
  • ON time: The time when a person’s movement symptoms are better controlled and daily function is improved. Some studies measure how much ON time patients have each day.
  • Troublesome dyskinesia: Unwanted extra movements that can happen during treatment. Some trials measure ON time without these movements.
  • Dyskinesia: Extra, involuntary movements that a person cannot control. Trials may separate troublesome from non-troublesome dyskinesia.
  • Placebo: A treatment that looks like the real study treatment but has no active drug. It is used to compare results fairly.
  • Phase 1: An early trial phase that usually checks how the treatment behaves in the body and whether it can be compared with another product.
  • Phase 2: A trial phase that looks more closely at early effectiveness and safety in a smaller group of patients.
  • Phase 3: A later trial phase that compares treatments in larger groups to see how well they work and how safe they are.
  • Phase 3b: A later study phase that often looks at additional real-world style questions after earlier Phase 3 work.
  • Pharmacokinetic endpoints: Measurements of how a drug moves through the body, such as peak level and overall exposure. These are used in the healthy volunteer study.

References

  1. https://clinicaltrials.gov/study/2023-504278-39-00
  2. https://clinicaltrials.eu/trial/56936/
  3. https://clinicaltrials.gov/study/2024-510629-24-00
  4. https://clinicaltrials.gov/study/2024-514852-34-01
  5. https://clinicaltrials.eu/trial/study-on-the-long-term-safety-of-nd0612-carbidopa-levodopa-infusion-for-patients-with-advanced-parkinsons-disease/
  6. https://clinicaltrials.gov/study/2025-521048-39-00
  7. https://clinicaltrials.gov/study/2025-521772-57-00
  8. https://clinicaltrials.gov/study/2025-524296-23-01
  9. https://clinicaltrials.gov/study/2023-504687-42-00