A Phase 1 interventional study of [18F]FDOPA and Carbidopa 200mg oral dose in Autonomic Failure, Pure Autonomic Failure and Parkinson Disease, sponsored by Daniel Claassen. Recruiting at 1 site in United States. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-03-16.
Sponsored by Daniel Claassen · Phase 1, Interventional, and Basic science
Alpha-synucleinopathies refer to age-related neurodegenerative and dementing disorders, characterized by the accumulation of alpha-synuclein in neurons and/or glia. The anatomical location of alpha-synuclein inclusions (Lewy Bodies) and the pattern of progressive neuronal death (e.g. caudal to rostral brainstem) give rise to distinct neurological phenotypes, including Parkinson's disease (PD), Multiple System Atrophy (MSA), Dementia with Lewy Bodies (DLB). Common to these disorders are the involvement of the central and peripheral autonomic nervous system, where Pure Autonomic Failure (PAF) is thought (a) to be restricted to the peripheral autonomic system, and (b) a clinical risk factor for the development of a central synucleinopathy, and (c) an ideal model to assess biomarkers that predict phenoconversion to PD, MSA, or DLB. Such biomarkers would aid in clinical trial inclusion criteria to ensure assessments of disease- modifying strategies to, delay, or halt, the neurodegenerative process. One of these biomarkers may be related to the neurotransmitter dopamine (DA) and related changes in the substantia nigra (SN) and brainstem. [18F]F-DOPA is a radiolabeled substrate for aromatic amino acid decarboxylase (AAADC), an enzyme involved in the production of dopamine. Use of this radiolabeled substrate in positron emission tomography (PET) may provide insight to changes in monoamine production and how they relate to specific phenoconversions in PAF patients. Overall, this study aims to identify changes in dopamine production in key regions including the SN, locus coeruleus, and brainstem to distinguish between patients with PD, MSA, and DLB, which may provide vital information to predict conversion from peripheral to central nervous system disease.
56 studies on the registry are indexed under Pure Autonomic Failure; 10 are open to participants now.
This study's planned enrollment of 40 is close to the median of 39 across 41 interventional studies indexed under Pure Autonomic Failure.
Browse Pure Autonomic Failure studies →This is the only study on the registry with Daniel Claassen as lead sponsor.
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Exclusion Criteria:
Also excluded are subjects incapable of giving informed written consent:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
All patients will receive \[18F\]F-DOPA for PET imaging to measure pre-synaptic dopamine in the brain.
Drug: [18F]FDOPA · Drug: Carbidopa 200mg oral dose · Drug: Entacapone 400mg oral dose
Patients will receive a 3-D emission scan following a 6-8 mCi slow bolus injection of \[18F\]FDOPA over a 30 second period. Serial scans are started simultaneously with the bolus injection of radiotracer and are obtained for approximately 95 minutes.
30 minutes prior to the PET scan, patients will receive the 200mg oral dose of carbidopa to prevent peripheral \[18F\]FDOPA metabolism to increase signal-to-noise ratio of the imaging.
Also known as: Lodosyn
30 minutes prior to the PET scan, patients will receive the 400mg oral dose of entacapone to prevent peripheral \[18F\]FDOPA metabolism to increase signal-to-noise ratio of the imaging.
Also known as: Comtan
Differences in FDOPA uptake across patient populations
Specific FDOPA uptake, Ki, will be calculated via a reference Logan plot to provide voxelwise measurements of FDOPA uptake. Mean uptake will be assessed in brain regions-of-interest in 40 participants to assess potential differences across different autonomic failure-related diseases.
Time frame: 95 minutes post-PET after start of PET imaging
Started Feb 2020 (actual). Primary completion is estimated for Feb 2027, 83 months after the start.
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Studies of the drug tested here: Fluorodopa F 18