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Evaluating udenafil for adolescents after Fontan procedure

Fontan Udenafil Exercise Longitudinal Assessment Trial (FUEL-2)

Phase 3 Interventional Mezzion Pharma Co. Ltd · NCT05918211

This study is testing if a new medication called udenafil can help teenagers who have had heart surgery feel better and exercise more easily.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment436 (estimated)
Ages12 Years to 18 Years
SexAll
SponsorMezzion Pharma Co. Ltd Industry-sponsored
Locations40 sites (Phoenix, Arizona and 39 other locations)
Trial IDNCT05918211 on ClinicalTrials.gov

What this trial studies

This study evaluates the safety and efficacy of udenafil, a selective PDE5 inhibitor, compared to a placebo in adolescents aged 12 to 19 who have undergone the Fontan procedure for single ventricle heart disease. Conducted over 26 weeks, this multicenter, randomized, double-blinded trial will measure changes in peak minute oxygen consumption using maximal cardiopulmonary exercise tests. Participants will be monitored for improvements in exercise capacity and overall heart function.

Who should consider this trial

Good fit: Ideal candidates are adolescents aged 12 to less than 19 years who have undergone the Fontan procedure.

Not a fit: Patients with significant heart complications or those listed for heart transplantation may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could enhance exercise capacity and quality of life for adolescents with Fontan physiology.

How similar studies have performed: Previous studies on PDE5 inhibitors have shown promise in improving exercise capacity in similar patient populations, suggesting potential for success in this approach.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

1. Males and females with Fontan physiology who are 12 to less than 19 years of age at enrollment.
2. Participant consent or parental/guardian consent and participant assent.
3. Participant fluency in primary language of country in which study is being conducted.
4. Current antiplatelet 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 3 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 mmHg between the regions proximal and distal to the obstruction as measured by either catheterization or echocardiography, obtained prior to screening for the trial.
8. Single lung physiology with greater than 80% flow to one lung.
9. Failure to achieve maximal exertion (defined as RER \< 1.10) on screening/baseline exercise test.
10. Peak minute oxygen consumption (VO2) less than 45% or ≥ 80% of predicated for age and gender at enrollment.
11. Severe ventricular dysfunction assessed qualitatively by clinical echocardiography within 6 months prior to enrollment.
12. Severe valvar regurgitation, ventricular outflow obstruction, or severe aortic arch obstruction assessed by clinical echocardiography within six months prior to enrollment.
13. History of significant renal (serum creatinine \> 2.0), hepatic (serum AST and/or ALT \> 3 times upper limit of normal), gastrointestinal or biliary disorders that could impair absorption, metabolism or excretion of orally administered medications.
14. Inability to complete exercise testing at baseline screening.
15. Subjects with a pacemaker whose heart rate at peak exercise is controlled by the extrinsic pacemaker as opposed to a native atrial rhythm.
16. History of PDE-5 inhibitor use within 12 months prior to enrollment. (Treatment is defined as chronic therapy as opposed to a single dose.)
17. History of any other medication for treatment of pulmonary hypertension within 3 months before study onset.
18. Known intolerance to oral udenafil.
19. Frequent use of medications or other substances that inhibit or induce CYP3A4.
20. Current use of alpha-blockers or nitrates.
21. Ongoing or planned participation in another research protocol that would either prevent successful completion of planned study testing or invalidate its results.
22. Noncardiac medical, psychiatric, and/or social disorder that would prevent successful completion of planned study testing or would invalidate its results.
23. Cardiac care, ongoing or planned, at a non-study center that would impede study completion.
24. 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 if sexually active.
25. Unable to abstain or limit intake of grapefruit juice and grapefruit containing drinks during the duration of the trial.
26. Refusal to provide written informed consent/assent.
27. In the opinion of the investigator, the subject is likely to be non-compliant with the study protocol.
28. History of clinically significant thromboembolic event, in the option of the site Principal Investigator, that may put the subject at increased risk of a subsequent event while participating in the study.
29. Coronavirus disease 2019 (COVID-19) vaccination or symptoms of COVID-19 infection within 7 days of Visit 1.
30. Not taking antiplatelet or anticoagulant therapy.

Where this trial is running

Phoenix, Arizona and 39 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Single Ventricle Heart DiseaseFontanMaximal Oxygen ConsumptionWork RateVO2 at VATVentilatory Efficiency
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.