Pyridostigmine for the Treatment of Constipation in Parkinson Disease

February 20, 2026 updated by: Lisa Deuel, MD, University of Vermont Medical Center
Constipation is a common and debilitating non-motor symptom of Parkinson disease (PD) that often precedes the onset of classic motor symptoms by decades. There is no standardized algorithm for managing constipation in this patient population, nor are there dedicated treatments. Studies suggest that constipation can affect quality of life to a significant degree, in many cases just as much as motor symptoms. There is an unmet need for effective treatment options for constipation in this patient population. The goal of this study is to determine the efficacy and safety of pyridostigmine as a treatment for chronic constipation in patients with PD.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This is a 13-15 week open-label, dose escalation trial of pyridostigmine 60-180mg three times a day (TID) for the treatment of constipation in patients with Parkinson disease.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
16

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Vermont
      • Burlington, Vermont, United States, 05401
        • Recruiting
        • University of Vermont Medical Center
        • Principal Investigator:
          • Lisa Deuel, MD
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

14 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Age ≥ 18 years
  2. Be able to provide signed informed consent
  3. Stated ability and willingness to comply with all study procedures
  4. Able to take oral medications
  5. Females of reproductive potential who are sexually active must be willing to use two of the following highly effective methods of contraception for the duration of study participation and for an additional 28 days after the end of study drug administration: barrier contraception (female condom, diaphragm, cervical cap with/without spermicide), hormonal contraception, or intrauterine device; OR one of the previously mentioned methods AND partner must use barrier contraception (male condom with/without spermicide)
  6. Males of reproductive potential who are sexually active must be willing to use the following highly effective methods of contraception for the duration of study participation and for an additional 28 days after the end of study drug administration: barrier contraception (male condom with/without spermicide) AND partner must be postmenopausal, use hormonal contraception, have an intrauterine device, or use barrier contraception (female condom, diaphragm, cervical cap with/without spermicide)

  7. Meet United Kingdom Parkinson's Disease Society Brain Bank Criteria:

    A. Diagnosis of a parkinsonism:

    • Bradykinesia, plus at least one of the following:
    • Muscular rigidity
    • 4-6 Hz resting tremor
    • Postural stability not caused by primary visual, vestibular, cerebellar or proprioceptive dysfunction

    B. At least three supportive criteria:

    • Unilateral onset of symptoms
    • Rest tremor
    • Progressive symptoms
    • Persistent asymmetry affecting the side of onset most
    • Excellent response to levodopa
    • Severe levodopa-induced chorea
    • Levodopa response for five years or more
    • Clinical course of 10 years or more

  8. Fulfill the ROME IV Criteria for Functional Constipation, with a specific requirement that the patient must have three or fewer defecations per week (criterion Ai):

    • Must include two or more of the following:

      i. Three or fewer defecations per week ii. Straining during > 25% of defecations iii. Lumpy or hard stools in > 25% of defecations iv. Sensation of incomplete evacuation for > 25% of defecations v. Sensation of anorectal obstruction/blockage for > 25% of defecations vi. Manual maneuvers to facilitate > 25% of defecations

    • Loose stools are rarely present without the use of laxatives
    • Insufficient criteria for irritable bowel syndrome
    • Criteria 1-3 must be fulfilled for at least three months with onset of symptoms at least six months prior to diagnosis

Exclusion Criteria:

  1. Diagnosis of atypical parkinsonism
  2. Diagnosis of drug-induced parkinsonism
  3. Diagnosis of vascular parkinsonism
  4. Known allergy to pyridostigmine bromide or other study drug components
  5. Current or recent (within 90 days of enrollment) use of pyridostigmine for any reason
  6. History of any bowel surgery
  7. History of bladder or bowel obstruction
  8. Severe asthma or chronic obstructive pulmonary disease

  9. Meet exclusion criteria noted in the UK Parkinson's Disease Society Brain Bank Criteria, at the PI's discretion:

    A.Exclusion of any of the following:

    • Repeated strokes with stepwise progression of parkinsonian features
    • Repeated head injury
    • Definite encephalitis
    • Oculogyric crises
    • Neuroleptic treatment at onset of symptoms
    • Greater than one affected relative
    • Sustained remission
    • Strictly unilateral features after 3 years
    • Supranuclear gaze palsy
    • Cerebellar signs
    • Early severe autonomic involvement
    • Early severe dementia
    • Babinski sign
    • Cerebral tumor or communicating hydrocephalus
    • Negative response to large doses of levodopa
    • 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine exposure
  10. Significant abnormalities on laboratory analysis (complete blood count, comprehensive metabolic panel, thyroid stimulating hormone) conducted at the screening visit or within the three months prior if available for review
  11. Significant abnormalities on screening electrocardiogram conducted at the screening visit or within the three months prior if available for review
  12. Positive pregnancy test (if female of child-bearing age)
  13. Antibiotic use within two weeks prior to enrollment

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Other: Pyridostigmine Bromide
Open Label
Drug: Pyridostigmine Bromide
Dose escalation trial of Pyridostigmine bromide oral tablets 60-180 mg TID for four weeks

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in number of spontaneous bowel movements per week after the study intervention
Time Frame: 13-15 Weeks
Participants will keep a Bowel Movement Journal during the four week Screening Phase, from which the pre-intervention average number of spontaneous bowel movements will be calculated. They will again keep a Bowel Movement Journal for the four weeks of the Treatment Phase, from which the postintervention average number of spontaneous bowel movements will be calculated.
13-15 Weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Changes from Baseline to the End of Study Visit in the Gastrointestinal Dysfunction Scale in Parkinson's Disease (GIDS-PD)
Time Frame: 9-11 Weeks

The Gastrointestinal Dysfunction Scale in Parkinson's Disease (GIDS-PD) is a PD-specific self-administered scale that evaluates various gastrointestinal symptoms including, but not limited to, constipation, and lifestyle factors that impact symptoms such as diet and physical activity. The GIDS-PD score is broken down into 3 subscores: constipation, bowel irritability, and upper GI. There are 12 items, and each item score is calculated by multiplying the frequency score and the severity score. The total score is calculated by adding the scores of items 1-12. The minimum score is 1 and the maximum score is 108.

While the GIDS-PD is typically completed based on symptoms over the past six months, the investigator will ask the participant to consider their symptoms over the past one month.
9-11 Weeks
Changes from Baseline to the End of Study Visit in the Cleveland Clinic Constipation Scoring System (CCCSS)
Time Frame: 9-11 Weeks

The Cleveland Clinic Constipation Scoring System (CCCSS) is a 0-30 point self-administered scale comprised of eight variables (i.e., frequency, difficulty, completeness, pain, time, assistance, failure and history) quantifying the degree of constipation. A score of 0 is normal while a score of 30 indicates severe constipation.

While the CCCSS is typically completed based on symptoms over the past six months, the investigator will ask the participants to consider their symptoms over the past one month.
9-11 Weeks
Changes from Baseline to the End of Study Visit in the International Parkinson and Movement Disorder Society Non-Motor Rating Scale (MDS-NMS)
Time Frame: 9-11 Weeks
The International Parkinson and Movement Disorder Society Non-Motor Rating Scale (MDS-NMS) is a revision of the Non-Motor Symptoms Scale (NMSS) and was developed to improve and refine the assessment of non-motor symptoms in Parkinson's disease (PD). This rater completed assessment measures frequency and severity of 13 non-motor domains, over 52 items and covers a range of key non-motor symptoms both PD and treatment related, and in greater depth, compared with the NMSS. The scale also has a new MDS-NMS Non-Motor Fluctuations (NMF) Subscale to assess changes in non-motor symptoms in relation to the timing of antiparkinsonian medications across 8 domains. The MDS-NMS is a valid and reliable rating scale that measures the burden of non-motor symptoms, including non-motor fluctuations, in PD patients.
9-11 Weeks
Number of adverse events and serious adverse events that occur during the trial
Time Frame: 13-15 Weeks
The investigator will monitor for any potential study drug related adverse events. The pyridostigmine bromide package insert does not recommend any routine safety assessments.
13-15 Weeks
Changes from Baseline to the End of Study Visit in the MDS-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Parts I-IV
Time Frame: 9-11 Weeks
The MDS sponsored revision of the Unified Parkinson's Disease Rating Sale (MDS-UPDRS) was developed to evaluate various aspects of Parkinson's disease including non-motor and motor experiences of daily living and motor complications. It includes a motor evaluation and characterizes the extent and burden of disease across various populations. The MDS-UPDRS is broken down into 4 parts: Part I (non-motor experiences of daily living), Part II (motor experiences of daily living), Part III (motor examination), and Part IV (motor complications).
9-11 Weeks
Changes from Baseline to the End of Study Visit in the Parkinson's Disease Questionnaire (PDQ-39).
Time Frame: 9-11 Weeks
The Parkinson's Disease Questionnaire (PDQ-39) is a self-administered survey assessing difficulties across eight dimensions of health, specifically, mobility, activities of daily living, emotional wellbeing, stigma, social support, cognition, communications and bodily discomfort. Each of 39 items are scored on a scale of 0-4, with higher scores indicating more profound difficulties. The PDQ-39 is completed based on symptoms over the past one month.
9-11 Weeks
Changes from Baseline to the End of Study Visit in Beck Depression Inventory-II (BDI-II)
Time Frame: 9-11 Weeks
The Beck Depression Inventory-II (BDI-II) is a self-administered survey assessing the presence and severity of depression. Each of 21 items are scored from 0-3, with higher scores indicating more severe depressive symptoms. The BDI-II is completed based on symptoms over the past two weeks.
9-11 Weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Vermont Medical Center

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Lisa M Deuel, MD, University of Vermont

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 10, 2022

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 31, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 12, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 31, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 3, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 23, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 20, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • STUDY00001877

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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