TheraRadar
Data updated: May 26, 2026

SINEMET (carbidopa)

DOPA Decarboxylase Inhibitors Trial Activity: Declining
CNS Approved 1975-05-02

SINEMET is indicated for the treatment of Parkinson's Disease; Post-Encephalitic Parkinsonism; Parkinsonism; Carbon Monoxide Intoxication; Manganese Intoxication; Nausea; Vomiting.

Source: FDA Label • Merck • Aromatic Amino Acid Decarboxylation Inhibitor

How SINEMET Works

Parkinson's disease symptoms are characterized by the depletion of dopamine in the corpus striatum. Because exogenous dopamine cannot cross the blood-brain barrier, it is ineffective as a direct treatment. Levodopa, the metabolic precursor of dopamine, is able to cross the blood-brain barrier, where it is converted into dopamine to alleviate motor symptoms. Carbidopa functions as an aromatic amino acid decarboxylase inhibitor, specifically blocking the peripheral conversion of levodopa to dopamine before it reaches the central nervous system. This mechanism increases the bioavailability of levodopa for the brain without carbidopa exerting a primary effect on the nervous system itself.

Development Insights

Acorda Therapeutics conducting 2 trials (40%)
4 indications explored (Focused)
acute pain (2 trials)
advanced parkinson's disease (1 trials)
parkinson's disease (1 trials)
1
Indication
--
Phase 3 Trials
1
Priority Reviews
51
Years on Market

Details

Status
Prescription
First Approved
1975-05-02
Routes
ORAL
Dosage Forms
TABLET

Companies

Active Ingredient: CARBIDOPA , LEVODOPA

SINEMET Approval History

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Original
New Indication
New Form
Label Update
180 FDA actions from 1975 to 2026
Mar 2026 SUPPL
Label · Labeling
Mar 2020 SUPPL
Mfg · Manufacturing (CMC)
Jul 2014 SUPPL
Label · Labeling

What SINEMET Treats

7 indications

SINEMET is approved for 7 conditions since its original approval in 1975. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Parkinson's Disease
  • Post-Encephalitic Parkinsonism
  • Parkinsonism
  • Carbon Monoxide Intoxication
  • Manganese Intoxication
  • Nausea
  • Vomiting
Source: FDA Label

SINEMET Competitive Set

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Filters applied: drops same-active-ingredient (505(b)(2) reformulations), route-mismatch (topical vs systemic), and cross-therapeutic-area matches in same-indication rings.

Drugs Similar to SINEMET

3 of 20

FDA-approved drugs for similar conditions. Compare mechanisms and indications to understand treatment alternatives.

STALEVO 125
CARBIDOPA
6 shared
ORION PHARMA
Shared indications:
Parkinson's DiseasePost-Encephalitic ParkinsonismCarbon Monoxide Intoxication +3 more
STALEVO 100
CARBIDOPA
4 shared
ORION PHARMA
Shared indications:
Parkinson's DiseasePost-Encephalitic ParkinsonismCarbon Monoxide Intoxication +1 more
STALEVO 150
CARBIDOPA
4 shared
ORION PHARMA
Shared indications:
Parkinson's DiseasePost-Encephalitic ParkinsonismCarbon Monoxide Intoxication +1 more
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Clinical Trial Registry

20 trials
Trial Sponsor ID Phase Status Title
NCT04520178 5-HTP only Pro00119483/00125176 Ph 2, Ph 3 recruiting Effects of 5HTP on the Injured Human Spinal Cord
NCT04325503 RES results posted HUM00156490 5U01AG061393-05 Ph 1, Ph 2 completed Neurobiological Drivers of Mobility Resilience: The Dopaminergic System
NCT01323374 FMS201 Droxidopa FMS201 Ph 2 completed Study To Assess The Clinical Benefit Of Droxidopa And Droxidopa/Carbidopa In Subjects With Fibromyalgia
NCT04000919 18.1268 Ph 2, Ph 3 suspended Effects of 5HTP and LDOPA on CNS Excitability After SCI
NCT03007888 results posted IPX203-B16-01 Ph 2 completed A Study to Assess the PK and Pharmacodynamics of IPX203 in Subjects With Advanced Parkinson's Disease
NCT00685919 results posted 101499 HL071784-05A1 Ph 2, Ph 3 completed Peripheral Dopamine in Postural Tachycardia Syndrome
NCT03055936 COMDOS1 results posted 3112005 Ph 1 completed Dose-finding Pharmacokinetic Study in Healthy Males
NCT03266965 20161186 W81XWH-16-1-0462 Ph 1 completed Histaminergic Basis of Central Fatigue in Multiple Sclerosis - A Novel Approach
NCT03115827 results posted VUMC54580 Ph 4 completed Norepinephrine-targeted Therapy for Action Control in Parkinson Disease
NCT01399905 results posted IRB00004133 Ph 2 completed High and Low Dose Carbidopa Treatment of Parkinson's Disease
NCT03887884 CVT-301-012 Ph 1 completed Pharmacokinetic Study of CVT-301 (Levodopa Inhalation Powder)
NCT00845000 results posted P05550 MK-3814-023 Ph 1 completed Acute Effects of Preladenant (SCH 420814) on Dyskinesia and Parkinsonism in Levodopa Treated Participants (P05550)
NCT02633839 CVT-301-007 Ph 1 completed A Study of the Safety and Levodopa Pharmacokinetics Following Single Dose Administration of CVT 301 (Levodopa Inhalation Powder) in Smoking and Non-Smoking Adults
NCT02633007 CVT-301-008 Ph 1 completed A Study of the Safety and Pharmacokinetics of Levodopa Following Administration of CVT 301 (Levodopa Inhalation Powder) in Adults With Asthma
NCT01212484 results posted 09-0011 Ph 3 completed Carbidopa for the Treatment of Nausea and Vomiting in Familial Dysautonomia
NCT01227655 BIPARKII results posted BIA-91067-302 2010-022366-27, BIA-91067-302 Ph 3 completed Efficacy and Safety of BIA 9-1067 in Idiopathic Parkinson's Disease Patients.
NCT01568073 results posted BIA-91067-301 2010-021860-13 Ph 3 completed Efficacy and Safety of BIA 9-1067 in Idiopathic Parkinson's Disease Patients With "Wearing-off" Phenomenon
NCT02116790 STU00083465 R01DE022746 Ph 2 withdrawn Efficacy of Co-administration of an NSAID With a Dopamine Agonist In Healthy Subjects
NCT01229332 ND0611/002 Ph 1, Ph 2 completed A Safety, Tolerability and Pharmacokinetic Study of ND0611 on the Top of Different Oral Dosage Forms of Levodopa/Carbidopa in Parkinson's Disease Patients
NCT01296464 PARTEST 2939136 Ph 2 completed Comparing Different Levodopa/Carbidopa/Entacapone Treatment Regimens
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Active Pipeline

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Ongoing clinical trials by development phase

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Key Completed Trials

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Completed studies with published results, ranked by significance

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Trial Timeline

Full development history with FDA approval milestones

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Understanding FDA Approval Types
Count Type What it means
- ORIG Original approval - drug first enters market
- SUPPL - Efficacy New indication (new disease/condition approved)
- SUPPL - Labeling Label text changes (warnings, dosing updates)
- SUPPL - Manufacturing Production changes (new facility)
- SUPPL - Chemistry Formulation changes (new dosage strength)

Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.

SINEMET FDA Label Details

Indications & Usage

FDA Label (PDF)

SINEMET is indicated for the treatment of Parkinson's Disease; Post-Encephalitic Parkinsonism; Parkinsonism; Carbon Monoxide Intoxication; Manganese Intoxication; Nausea; Vomiting.

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Data Sources

Data sourced from official FDA and NIH databases. Click links to verify on original sources.

How We Calculate These Metrics

Trial Activity Stage

Measures the current development activity pattern based on trial phases, status, and trends. Important: This measures R&D activity, not commercial lifecycle.

Trial statuses: "Active" means recruiting or ongoing. "Completed" means reached planned endpoint. "Terminated" means stopped early—often due to safety, efficacy, or business reasons.

  • Growth: High proportion of early-phase trials (Phase 1/2), active development
  • Expansion: Significant Phase 3 activity, approaching or pursuing approvals
  • Mature: Substantial Phase 4 post-marketing studies
  • Stable: Mixed phase distribution, steady development
  • Declining: Low active trial ratio, reduced R&D investment