A Extension Study of Udenafil in Adolescents (FUELExten)

November 25, 2025 updated by: Mezzion Pharma Co. Ltd

A Phase III Extension Study of Udenafil in Adolescents With Single Ventricle Physiology After Fontan Palliation

This study is a 12-month (52 week) safety extension study to supplement the FUEL Phase III clinical trial to provide safety information regarding the long-term use of udenafil in adolescents with single ventricle congenital heart disease.

Study Overview

Status

Status

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

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 will be an open-label extension study. All enrolled subjects will be provided with udenafil for the duration of the study. Subjects completing the Phase III FUEL study will be eligible for recruitment. Additional subjects will be recruited as needed to ensure a minimum of 300 total subjects enroll. Safety, pharmacodynamic and quality of life data will be collected and analyzed.

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 (Actual)

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.
301

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 3

Contacts and Locations

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

Study Locations

  • Canada
    • Ontario
      • Toronto, Ontario, Canada, ON M5G 1X8
        • The Hospital for Sick Children
  • South Korea
      • Seoul, South Korea, 110-744
        • Seoul National University Children's Hospital
    • Gyeonggi-do
      • Bucheon-si, Gyeonggi-do, South Korea, 14754
        • Sejong General Hospital
  • United States
    • Arizona
      • Phoenix, Arizona, United States, 85016
        • Phoenix Children's Hospital/Children's Heart Center at Phoenix Children's Hospital
    • California
      • Los Angeles, California, United States, 90048
        • Cedars/Sinai Heart Institute
      • San Diego, California, United States, 92123
        • Rady Children's Hospital
    • Colorado
      • Aurora, Colorado, United States, 80045
        • Children's Hospital Colorado
    • Delaware
      • Wilmington, Delaware, United States, 19803
        • Nemours Cardiac Center/Alfred I. duPont Hospital for Children
    • District of Columbia
      • Washington D.C., District of Columbia, United States, 20008
        • Children's National Medical Center
    • Florida
      • St. Petersburg, Florida, United States, 33701
        • Johns Hopkins All Children's Heart Institute
    • Georgia
      • Atlanta, Georgia, United States, 30322
        • Children's Healthcare of Atlanta
    • Indiana
      • Indianapolis, Indiana, United States, 46201
        • Riley Hospital for Children/Herman B. Wells Center for Pediatric Research
    • Massachusetts
      • Boston, Massachusetts, United States, 02115
        • Boston Children's Hospital
    • Michigan
      • Ann Arbor, Michigan, United States, 48109-4204
        • University of Michigan Congenital Heart Center/C.S. Mott Children's Hospital
    • Missouri
      • Kansas City, Missouri, United States, 64108
        • Children's Mercy Hospital Kansas City
      • St Louis, Missouri, United States, 63110
        • Washington University St. Louis/St.Louis Children's Hospital
    • New York
      • New York, New York, United States, 10032
        • Children's Hospital of New York
    • Ohio
      • Cincinnati, Ohio, United States, 45229
        • Cincinnati Children's Hospital Medical Center
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • Children's Hospital of Philadelphia
    • South Carolina
      • Charleston, South Carolina, United States, 29425
        • Medical University of South Carolina
    • Texas
      • Houston, Texas, United States, 77030
        • Texas Children's Hospital
    • Utah
      • Salt Lake City, Utah, United States, 84113
        • Primary Children's Medical Hospital/Dept. of Pediatric Cardiology
    • Washington
      • Seattle, Washington, United States, 98105
        • Seattle Children's Hosptial
    • Wisconsin
      • Milwaukee, Wisconsin, United States, 53226
        • Children's Hospital of Wisconsin

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

12 years to 18 years (Child, Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Males and females with Fontan physiology who participated in the FUEL trial or, if they did not participate in FUEL, those who are 12 to less than 19 years of age at enrollment.
  2. Participant consent or parental/guardian consent and participant assent.
  3. Participant fluent in English, Spanish, or Korean.
  4. Current anti-platelet or anticoagulant therapy.

Exclusion Criteria:

  1. Height < 132 cm.
  2. Weight < 40 kg.
  3. Hospitalization for acute decompensated heart failure within the last 12 months.
  4. Current intravenous inotropic drugs.
  5. Undergoing evaluation for heart transplantation or listed for transplantation.
  6. Diagnosis of active protein losing enteropathy or plastic bronchitis within the last three years, or a history of liver cirrhosis.
  7. Known Fontan baffle obstruction, branch pulmonary artery stenosis, or pulmonary vein stenosis resulting in a mean gradient of > 4 mm Hg between the regions proximal and distal to the obstruction as measured by either catheterization or echocardiography.
  8. Single lung physiology.
  9. Maximal VO2 less than 50% of predicted for age and gender at enrollment.
  10. Severe ventricular dysfunction assessed qualitatively by clinical echocardiography within six months prior to enrollment.
  11. Severe valvar regurgitation, ventricular outflow obstruction, or aortic arch obstruction assessed by clinical echocardiography within six months prior to enrollment.
  12. Significant renal, hepatic, gastrointestinal or biliary disorders that could impair absorption, metabolism or excretion of orally administered medications.
  13. Inability to complete exercise testing at baseline screening.
  14. History of PDE-5 inhibitor use (with the exception of FUEL participation) within 3 months before study onset.
  15. Use of any other drug to treat pulmonary hypertension within 3 months before study onset.
  16. Known intolerance to oral udenafil.
  17. Frequent use of medications or other substances that inhibit or induce CYP3A4.
  18. Current use of alpha-blockers or nitrates.
  19. Ongoing or planned participation in another research protocol that would either prevent successful completion of planned study testing or invalidate its results.
  20. Noncardiac medical, psychiatric, and/or social disorder that would prevent successful completion of planned study testing or would invalidate its results.
  21. Cardiac care, ongoing or planned, at a non-study center that would impede study completion.
  22. For females: Pregnancy at the time of screening, pregnancy planned before study completion, or refusal to use an acceptable method of contraception for study duration.
  23. Unable to abstain or limit intake of grapefruit juice during the duration of the trial.
  24. Refusal to provide written informed consent/assent.
  25. In the opinion of the primary care physician, the subject is likely to be non-compliant with the study protocol.
  26. History of clinically significant thromboembolic event, as adjudicated by study Investigators.

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.
Experimental: Drug
Udenafil administered for 52 weeks
Drug: Udenafil
Active drug

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
Treatment-Emergent Adverse Events
Time Frame: 52 Weeks
Summary of Treatment Emergent Adverse Events
52 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
Change in Maximal VO2
Time Frame: 52 Weeks
Change in Maximal VO2 from baseline to 52 weeks
52 Weeks
Change in Log-transformed Reactive Hyperemia Index (lnRHI)
Time Frame: 52 Weeks
Change from baseline to 52 weeks in Log-transformed Reactive Hyperemia Index (lnRHI). The Reactive Hyperemia Index (RHI) is the ratio of the amount of blood flow after the release of a period of vessel occlusion relative to baseline amount of blood flow. Because the amount of blood does not decrease after release of vessel occlusion, the minimum value for the RHI is 1.0, which would indicate no change in blood flow. There is no upper limit for this ratio, and higher values are generally thought to represent a healthier endothelial response. In this study, as in other studies, we used the natural log of RHI (lnRHI) to normalize the data.
52 Weeks
Change in Serum BNP
Time Frame: 52 Weeks
Change in Serum BNP from baseline to 52 weeks
52 Weeks
Change in Myocardial Performance Index (MPI)
Time Frame: 52 Weeks
Change in Myocardial Performance Index from baseline to 52 weeks
52 Weeks
Change in PedsQL Physical Functioning (Child Reported)
Time Frame: 52 Weeks
Change in PedsQL Physical Functioning (Child Reported) from baseline to 52 weeks. The Pediatric Quality of Life Inventory (PedsQL) - Physical Function Scale is calculated from a child's answers to a short questionnaire. The range of possible scores is 0-100, and higher scores indicate better reported physical function.
52 Weeks
Change in PedsQL Physical Functioning (Parent Reported)
Time Frame: 52 Weeks
Change in PedsQL Physical Functioning (Parent Reported) from baseline to 52 weeks. The Pediatric Quality of Life Inventory (PedsQL) - Physical Function Scale is calculated from parent's answers to a short questionnaire. The range of possible scores is 0-100, and higher scores indicate better reported physical function.
52 Weeks
Change in PedsQL Psychosocial Health Summary Score (Child Reported)
Time Frame: 52 Weeks
Change in PedsQL Psychosocial Health Summary Score (Child reported) from baseline to 52 weeks. The Pediatric Quality of Life Inventory (PedsQL) - Psychosocial Health Summary Scale is calculated from a child's answers to a short questionnaire. The range of possible scores is 0-100, and higher scores indicate better reported psychosocial health.
52 Weeks
Change in PedsQL Psychosocial Health Summary Score (Parent Reported)
Time Frame: 52 Weeks
Change in PedsQL Psychosocial Health Summary Score (Parent reported) from baseline to 52 weeks. The Pediatric Quality of Life Inventory (PedsQL) - Psychosocial Health Summary Scale is calculated from parent's answers to a short questionnaire. The range of possible scores is 0-100, and higher scores indicate better reported psychosocial health.
52 Weeks
Change in PedsQL Functional Health Status Score (Child Reported)
Time Frame: 52 Weeks
Change in PedsQL Functional Health Status Score (Child reported) from baseline to 52 weeks. The Pediatric Quality of Life Inventory (PedsQL) - Functional Health Status Score is calculated from a child's answers to a short questionnaire. The range of possible scores is 0-100, and higher scores indicate better functional health status.
52 Weeks
Change in PedsQL Functional Health Status Score (Parent Reported)
Time Frame: 52 Weeks
Change in PedsQL Functional Health Status Score (Parent reported) from baseline to 52 weeks. The Pediatric Quality of Life Inventory (PedsQL) - Functional Health Status Score is calculated from parent's answers to a short questionnaire. The range of possible scores is 0-100, and higher scores indicate better functional health status.
52 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.
Mezzion Pharma Co. Ltd

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Heart, Lung, and Blood Institute (NHLBI)

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: Steve Paridon, MD, Children's Hospital of Philadelphia

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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.
February 6, 2017

Primary Completion (Actual)

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 30, 2019

Study Completion (Actual)

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 20, 2022

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).
January 5, 2017

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.
January 5, 2017

First Posted (Estimated)

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.
January 6, 2017

Study Record Updates

Last Update Posted (Estimated)

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.
December 9, 2025

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.
November 25, 2025

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.
November 1, 2025

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.
  • PHN-Udenafil-03
  • U01HL068270 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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