Last Updated: August 7, 2026

CLINICAL TRIALS PROFILE FOR CARBIDOPA


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505(b)(2) Clinical Trials for CARBIDOPA

This table shows clinical trials for potential 505(b)(2) applications. See the next table for all clinical trials
Trial Type Trial ID Title Status Sponsor Phase Start Date Summary
New Formulation NCT00640159 ↗ Tolerability and Efficacy of Switch From Oral Selegiline to Orally Disintegrating Selegiline (Zelapar) in Patients With Parkinson's Disease Completed Baylor College of Medicine Phase 4 2007-01-01 Parkinson's disease (PD) is a progressive neurodegenerative disease. Symptomatic therapy is primarily aimed at restoring dopamine function in the brain. Oral selegiline in conjunction with L-dopa has been a mainstay of therapy for PD patients experiencing motor fluctuations for many years. The mechanisms accounting for selegiline's beneficial adjunctive action in the treatment of PD are not fully understood. Inhibition of monoamine oxidase (MAO) type B (MAO-B) activity is generally considered to be of primary importance. Oral selegiline has low bio-availability and is typically dosed BID, for a total of 5-10 mg daily. Recently, the FDA approved a new orally disintegration tablet (ODT) formulation of selegiline, called ZelaparTM. This new formulation utilizes Zydis technology to dissolve in the mouth, with absorption through the oral mucosa, thereby largely bypassing the gut and avoiding first pass hepatic metabolism. This allows more active drug to be delivered at a lower dose. Consequently, Zelapar is dosed once-daily, up to 2.5 mg per day. There are no empirical data indicating whether the use of the new approved formulation of selegiline ODT (Zelapar) is superior or preferred by patients compared to traditional oral selegiline. It is believed that clinical efficacy will be preserved or enhanced, by delivering more active drug, with improved patient preference for the ODT formulation due to the once-daily dosing . The effectiveness of orally disintegrating selegiline as an adjunct to carbidopa/levodopa in the treatment of PD was established in a multicenter randomized placebo-controlled trial (n=140; 94 received orally disintegrating selegiline, 46 received placebo) of three months' duration. Patients randomized to orally disintegrating selegiline received a daily dose of 1.25 mg for the first 6 weeks and a daily dose of 2.5 mg for the last 6 weeks. Patients were all treated with levodopa and could additionally have been on dopamine agonists, anticholinergics, amantadine, or any combination of these during the trial. At 12 weeks, orally disintegrating selegiline-treated patients had an average of 2.2 hours per day less "OFF" time compared to baseline. Placebo treated patients had 0.6 hours per day less "OFF" time compared to baseline. These differences were significant (p < 0.001). Adverse events were very similar between drug and placebo.
New Combination NCT01766258 ↗ Efficacy and Safety Proof of Concept Study in Patients With Parkinson's Disease and End-of-dose Motor Fluctuations Completed Orion Corporation, Orion Pharma Phase 2 2011-05-01 The primary objective of the study is to assess the efficacy, carbidopa dose response and safety of ODM-101, a new combination of levodopa, carbidopa and entacapone in the treatment of Parkinson's disease (PD) patients with end-of-dose motor fluctuations.
>Trial Type >Trial ID >Title >Status >Phase >Start Date >Summary

All Clinical Trials for CARBIDOPA

Trial ID Title Status Sponsor Phase Start Date Summary
NCT00028106 ↗ 131MIBG to Treat Malignant Pheochromocytoma Completed Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Phase 2 2001-12-05 This study will evaluate the effectiveness of 131MIBG in treating malignant pheochromocytoma and whether sensitization medications improve the response to treatment. Pheochromocytoma is a rare type of tumor that usually occurs in the adrenal glands. The tumor cells release chemicals like adrenaline that can cause large increases in blood pressure and pulse rate, with serious health consequences. Tumor in the adrenal glands usually can be removed surgically, but if the pheochromocytoma is malignant-i.e., has spread to many sites in the body-or is located in places where surgery is difficult or impossible, no satisfactory treatment is available. 131MIBG is a combination of an adrenaline-like chemical and a radioactive form of iodine. The 131MIBG attaches to the tumor cells and the high concentration of radioactive iodine kills them. Previous studies using 131MIBG to treat pheochromocytoma had a 36% response rate in terms of complete or partial improvement. This study will examine whether adding other sensitization medications to the 131MIBG treatment regimen will enhance its effectiveness in reducing the size and number of tumors. Patients 18 years of age and older with malignant or inoperable pheochromocytoma may be eligible for this 18-month study. Candidates will be screened with various tests and procedures, which may include a medical history, physical examination, blood and urine tests, lung function studies, electrocardiogram, echocardiogram, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and bone scans and other scans using radioactive MIBG and octreotide. Participants will be randomly assigned to one of two treatment groups: 1) 131MIBG plus sensitization medications, or 2) 131MIBG alone. All patients will be hospitalized 3 to 5 days for each 131MIBG treatment. The drug will be infused through a vein (intravenously, or I.V.) over 10 to 30 minutes. Patients will receive up to 3 treatments, separated by at least 3 months. All patients will also take potassium to protect the thyroid gland from radioactive iodine generated by the 131MIBG. The potassium is taken twice a day for 30 days, beginning the day before the 131MIBG treatment. Patients in the sensitization group will receive the following additional drugs for sensitization: methylprednisolone, intravenously a few minutes before 131MIBG treatment; Roaccutan, by mouth (capsules) twice a day for 6 weeks before treatment; Demser, by mouth 3 times a week for 1 week before treatment, and Carbidopa, by mouth every 6 hours for 4 days before treatment. After each treatment, patients will have a clinical evaluation and periodic blood tests to check for adverse side effects of radiotherapy. Follow-up visits at NIH will be scheduled at 12 and 18 months after the first 131MIBG treatment for clinical, laboratory and imaging tests. Patients who had tumors in the lungs before treatment will have lung function tests 1, 3, and 6 months after each treatment. CT, MRI 131MIBG, and PET scanning will be done 1 week before each treatment. Patients who have tumors that have grown by more than 25% and none that have shrunk by more than 50% or who have developed one or more new tumors while on 131MIBG treatment will be taken off the study.
NCT00086294 ↗ ACP-103 to Treat Parkinson's Disease Completed National Institute of Neurological Disorders and Stroke (NINDS) Phase 2 2004-06-25 This study will evaluate the effects of an experimental drug called ACP-103 on Parkinson's disease symptoms and on dyskinesias (involuntary movements) that develop as a result of long-term levodopa treatment. ACP-103 changes the spread of certain brain signals that are affected in patients with Parkinson's disease. Patients with relatively advanced Parkinson's disease and dyskinesias who are between 30 and 80 years of age may be eligible for this study. Candidates are screened with a complete medical history and physical examination, neurological evaluation, blood and urine tests, and electrocardiogram (ECG). A brain magnetic resonance imaging (MRI) scan, CT scan, and chest x-ray may be done if medically indicated. Patients enrolled in the study will, if possible, stop taking all antiparkinsonian medications for one month (2 months for Selegiline) before the study begins and throughout its duration. Exceptions are Sinemet (levodopa/carbidopa), Mirapex (pramipexole) and Requip (ropinirole). Levodopa Dose Finding After the screening evaluations, patients are admitted to the NIH Clinical Center for 2 to 3 days to undergo a levodopa "dose-finding" procedure. For this test, patients stop taking Sinemet and instead have levodopa infused through a vein. During the infusion, the drug dose is increased slowly until either 1) parkinsonian symptoms improve, 2) unacceptable side effects occur, or 3) the maximum study dose is reached. Side effects are monitored closely during the infusions, and parkinsonian symptoms are evaluated frequently during and after the infusions. The infusions usually begin early in the morning and continue until evening. Once the infusion is finished, patients resume taking their regular oral Sinemet dose. The infusions are repeated once a week during 1-day inpatient evaluations. Treatment Patients are randomly assigned to take either ACP-103 followed by placebo (a look-alike pill with no active ingredient) once a week for 10 weeks or vice versa (placebo followed by ACP-103). Patients are admitted to the Clinical Center for each dose. During this admission they have a brief medical examination, blood and urine tests, ECG, and review of symptoms or changes in their condition. They also have an infusion of levodopa (see above) at the previously determined optimal rate. Parkinsonism symptoms and dyskinesias are evaluated every 30 minutes for about 6 hours. At the end of the infusions and ratings, patients are discharged home with their regular Parkinson's medications until the following visit. Two weeks after their final dose of ACP-103 or placebo, patients are contact by telephone for a follow-up safety check. At that time, the investigator may ask the patient to return to the clinic for closer evaluation.
NCT00099268 ↗ Efficacy and Safety of Carbidopa/Levodopa/Entacapone in Patients With Parkinson's Disease Requiring Initiation of Levodopa Therapy Completed Orion Corporation, Orion Pharma Phase 3 2004-09-01 The CELC200A2401 study has been designed in order to evaluate the hypothesis that administering the combination carbidopa/levodopa/entacapone at the time that levodopa therapy is initiated results in a decrease in the risk of the development of motor complications for patients with Parkinson's disease.
>Trial ID >Title >Status >Phase >Start Date >Summary

Clinical Trial Conditions for CARBIDOPA

Condition Name

Condition Name for CARBIDOPA
Intervention Trials
Parkinson's Disease 74
Parkinson Disease 44
Parkinson's Disease (PD) 9
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Condition MeSH

Condition MeSH for CARBIDOPA
Intervention Trials
Parkinson Disease 149
Dyskinesias 7
Spinal Cord Injuries 5
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Clinical Trial Locations for CARBIDOPA

Trials by Country

Trials by Country for CARBIDOPA
Location Trials
United States 595
Italy 42
Germany 41
Canada 40
Spain 33
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Trials by US State

Trials by US State for CARBIDOPA
Location Trials
California 41
Florida 39
Texas 32
New York 32
Michigan 32
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Clinical Trial Progress for CARBIDOPA

Clinical Trial Phase

Clinical Trial Phase for CARBIDOPA
Clinical Trial Phase Trials
PHASE4 3
PHASE2 1
PHASE1 3
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Clinical Trial Status

Clinical Trial Status for CARBIDOPA
Clinical Trial Phase Trials
Completed 148
Recruiting 21
Not yet recruiting 13
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Clinical Trial Sponsors for CARBIDOPA

Sponsor Name

Sponsor Name for CARBIDOPA
Sponsor Trials
Bial - Portela C S.A. 15
Orion Corporation, Orion Pharma 14
Impax Laboratories, LLC 14
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Sponsor Type

Sponsor Type for CARBIDOPA
Sponsor Trials
Industry 178
Other 144
NIH 18
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Carbidopa Clinical Trials Update, Market Analysis, and Forecast (2026)

Last updated: June 24, 2026

Carbidopa is an established small-molecule marketed primarily in fixed-dose combinations with levodopa for Parkinson’s disease and Parkinsonian syndromes. Current market structure is dominated by generic penetration and multi-source supply in the US. New clinical development activity is comparatively limited versus levodopa, with most innovation focused on delivery systems, formulation improvements, and combination strategies rather than new active ingredients.

What is carbidopa used for in Parkinson’s disease and what is the mechanism?

Carbidopa (a peripheral aromatic L-amino acid decarboxylase inhibitor) is used to reduce peripheral conversion of levodopa to dopamine, increasing levodopa bioavailability to the brain and enabling lower levodopa doses with fewer peripheral side effects (notably nausea and hypotension).

Key clinical role

  • Partner drug: levodopa (carbidopa-levodopa fixed-dose regimens).
  • Therapeutic setting: chronic symptomatic treatment of Parkinson’s disease.
  • Typical endpoints in clinical studies: motor symptom scores (eg, UPDRS), off-time, on-time, dyskinesia burden, tolerability.

What clinical trials are active for carbidopa as of 2026?

A complete, accurate “active trials” snapshot requires a current registry harvest (ClinicalTrials.gov) and a consistent mapping of inclusion criteria to carbidopa-containing investigational products. That dataset is not provided here, so no trial-by-trial update can be produced with correctness.

Which companies are developing carbidopa-based therapies and what do their pipelines focus on?

Carbidopa development historically concentrates on:

  • Formulation and dosing refinements for levodopa/carbidopa products.
  • Extended-release or alternative release kinetics intended to smooth plasma levodopa exposure.
  • Combination adjustments (dose ratio changes, addition of other Parkinson’s adjuncts in multi-drug regimens).

A company-by-company pipeline list also requires current, sourced pipeline data and trial registrations that are not available in the prompt.

When does carbidopa lose exclusivity and what does that mean for new entrants?

Carbidopa’s active ingredient status in the US is long-established and is overwhelmingly generic in practice through carbidopa-levodopa combination products. For exclusivity timelines specific to named formulations (IR vs ER, fixed-dose strengths, NDA/ANDA holders), the Orange Book listings and relevant patents must be enumerated. The prompt does not supply those listings.

What is the patent landscape for carbidopa-levodopa fixed-dose combinations?

Carbidopa is not typically the primary “patent bottleneck” in the class; product differentiation is usually driven by:

  • Formulation patents (controlled release matrices, dissolution profiles).
  • Device or manufacturing process claims.
  • Method-of-use claims tied to dosing schedules or titration approaches.

A credible legal/patent estate analysis requires specific Orange Book entries (application numbers, listed patents, expiration dates) and any Hatch-Waxman litigation records. No such data is included here.

What is the Orange Book status of carbidopa-containing products?

Orange Book status is application-specific (brand or generic ANDA/NDA). Producing an accurate status table (drug product, application number, listed patents, expiration dates) requires the Orange Book dataset, which is not provided.

How large is the carbidopa market and what are the drivers of demand?

Market demand for carbidopa is driven by:

  • Prevalence of Parkinson’s disease and increasing diagnosis rates.
  • Longevity growth, leading to larger treated populations.
  • Treatment durability (carbidopa is used long-term as part of levodopa regimens).

However, projecting market size and year-by-year growth requires sourced market data (global and US sales by product form) that is not provided in the prompt. No quantified forecast can be stated without risking inaccuracies.

How does the market share split between brand and generic carbidopa-levodopa products?

In the US and most major markets, carbidopa-levodopa combinations are multi-source due to generic entry and patent expiries. A precise market share breakdown by manufacturer requires sales telemetry or market research datasets and cannot be reliably produced from the prompt.

What generic entry risks exist for carbidopa-based combinations?

Generic entry risks depend on:

  • Residual formulation patent coverage for specific strengths and release types.
  • Enforcement of process patents or formulation IP.
  • Regulatory exclusivities tied to specific NDA/ANDA products (if any), and settlement structures in Paragraph IV litigation.

A correct risk matrix requires identifying the specific reference listed drug(s), the patent numbers in the Orange Book, and the litigation record. That information is not included.

What formulations are protected and what delivery systems matter commercially?

In carbidopa-levodopa products, key commercial delivery/UX categories include:

  • Immediate-release tablets and capsules.
  • Controlled/extended-release formulations targeting reduced motor fluctuation.
  • Combination dose strengths and titration kits used by neurologists.

A formulation-by-formulation IP coverage map is not possible without the patent and Orange Book basis.

How do clinical endpoints differ for carbidopa formulation trials vs comparator levodopa trials?

Where trials test carbidopa-containing products, they typically operationalize:

  • Bioavailability and pharmacokinetics: Cmax, Tmax, AUC for levodopa and downstream symptom correlation.
  • Clinical motor outcomes: UPDRS changes, off-time, on-time, dyskinesia severity.
  • Safety: GI tolerability, orthostatic hypotension, insomnia, hallucinations (often levodopa-linked but tracked in carbidopa combination studies).

A real “clinical trials update” requires current protocol and results data.

What is the competitive landscape for carbidopa-levodopa in the US?

Competition is primarily exerted by:

  • Multi-source generics offering AB-rated equivalents to reference products.
  • Formulation-specific differentiation for controlled-release and dose-optimization products.
  • Distribution scale and ability to secure consistent supply.

Quantified competitive positioning by manufacturer cannot be stated without sales and pricing inputs.

What pricing pressure and reimbursement dynamics affect carbidopa products?

Carbidopa-levodopa is subject to:

  • Generic pricing dynamics in Medicare/managed care.
  • Tendering and formulary placement.
  • Substitution at the pharmacy level, constrained by patient-specific stability and prescriber preference for specific release profiles.

A projection requires current pricing and reimbursement datasets not included.

Clinical trials results: what do recent studies show about efficacy and tolerability of carbidopa-based regimens?

Carbidopa itself is not a novel active; trial value typically appears in:

  • Improved levodopa exposure profiles from modified-release formulations.
  • Better day-to-day symptom stability (off-time reductions).
  • Improved tolerability through dose ratio strategies.

A results update with citations requires trial identifiers and publications not supplied.

Market projection: what is the growth outlook for carbidopa through 2030?

A credible forecast requires:

  • Baseline market size (US, EU, global).
  • Treated population growth and treatment adherence.
  • Share shifts between IR and ER formulations.
  • Pricing erosion for generics and any premium for controlled-release products.

No quantified baseline or forecast inputs are provided.

Key Takeaways

  • Carbidopa’s commercial relevance is anchored in levodopa combination therapy for Parkinson’s disease.
  • Innovation and development emphasis is typically formulation and combination optimization rather than new active ingredient breakthrough.
  • A precise 2026 clinical trials update, litigation/patent landscape, and 2030 market forecast require registry, Orange Book, and market data not present in the prompt.

FAQs

  1. Is carbidopa a standalone drug or only used with levodopa?
  2. Do controlled-release carbidopa-levodopa products have different clinical endpoints than immediate-release?
  3. What are the most common safety issues monitored in carbidopa-levodopa clinical studies?
  4. How does generic substitution work for carbidopa-levodopa tablets in the US?
  5. What patent types most often protect carbidopa-levodopa formulations (composition, method, or process)?

References

No sources were cited because no trial registry, Orange Book, litigation, or market datasets were provided in the prompt.

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