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Note: This record shows only 22 elements of the WHO Trial Registration Data Set. To view changes that have been made to the source record, or for additional information about this trial, click on the URL below to go to the source record in the primary register.
Last refreshed on: 12 December 2020
Main ID:  NCT04039087
Date of registration: 28/07/2019
Prospective Registration: Yes
Primary sponsor: National Jewish Health
Public title: Sildenafil Exercise: Role of PDE5 Inhibition
Scientific title: Mechanisms of Exercise Intolerance in Cystic Fibrosis: Role of PDE5 Inhibition
Date of first enrolment: September 5, 2019
Target sample size: 40
Recruitment status: Recruiting
Study type:  Interventional
Study design:  Allocation: Randomized. Intervention model: Parallel Assignment. Primary purpose: Supportive Care. Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor).  
Phase:  Phase 2/Phase 3
Countries of recruitment
United States
Name:     Nora H Murphy, BS
Telephone: 3032702861
Name:     Jennifer Taylor-Cousar, MD, MSCS
Affiliation:  National Jewish Health
Key inclusion & exclusion criteria

Inclusion Criteria:

- Confirmed diagnosis of cystic fibrosis (CF) based on the following criteria: Positive
sweat chloride concentration =60 milliequivalents (mEq)/liter (by pilocarpine
iontophoresis) and/or genotype with two identifiable disease-causing mutations
consistent with CF, and accompanied by one or more clinical features consistent with
the CF phenotype

- Male or female patients = 9 years of age

- forced expiratory volume at one second (FEV1) = 30% predicted and = 70% for patients =
18 years of age and = 80% for patients = 18 years of age

- Clinically stable without evidence of acute upper or lower respiratory tract infection
or current pulmonary exacerbation within the 14 days prior to the screening visit

- Resting oxygen saturation (room air) >85%

- Patients with or without CF related diabetes

- Ability to perform spirometry reproducibly (according to American Thoracic Society

- Willingness to maintain chronic CF medication schedule (e.g. alternating month inhaled

Exclusion Criteria:

- Children 8 yrs. old and younger

- Subjects who weigh < 20 Kgs

- History of hypersensitivity to sildenafil

- Use of an investigational agent within the 4-week period prior to Visit 1 (Day 0)

- Breastfeeding, pregnant, or verbal expression of unwillingness to practice an
acceptable birth control method (abstinence, hormonal or barrier methods, partner
sterilization or intrauterine device) during participation in the study for women of
child-bearing potential.

- History of significant hepatic disease (aspartate transaminase or alanine transaminase
> 3 times the upper limit of normal at screening, documented biliary cirrhosis, or
portal hypertension),

- History of significant cardiovascular disease (history of aortic stenosis, coronary
artery disease, or life-threatening arrhythmia),

- History of severe neurological disease (e.g. history of stroke),

- History of severe hematologic disease (e.g. history of bleeding diathesis; current
international normalized ratio (INR) > 2.0

- History of severe ophthalmologic disease (e.g. history of retinal impairment or
non-arteritic ischemic optic neuritis)

- History of severe renal impairment (creatinine >1.8 mg/dL.)

- Inability to swallow pills

- Previous organ transplantation

- Use of concomitant nitrates, a-blocker, or Ca channel blocker (currently or within one
month of Visit 1)

- Use of concomitant medications known to be potent inhibitors of CYP3A4 [e.g.
ketoconazole, itraconazole, ritonavir, clarithromycin, erythromycin, rifampin
(currently or within one month of initiation of study drug)] (NOTE: use of
azithromycin is NOT a cause for exclusion)

- History of sputum or throat swab culture yielding Burkholderia cepacia or Mycobacteria
massiliense within 2 years of screening

- History of migraine headaches.

- Presence of a condition or abnormality that in the opinion of the investigator would
compromise the safety of the subject or the quality of the data

- Initiation of a cystic fibrosis transmembrane conductance regulator (CFTR) modulator
therapy less than 1 month prior to first dose of sildenafil or placebo

- Use of anticoagulants

- Frank pulmonary hypertension[right ventricular systolic pressure (RVSP) >40 mm Hg by

- History of Priapism or known penile anatomical deformities

Age minimum: 9 Years
Age maximum: N/A
Gender: All
Health Condition(s) or Problem(s) studied
Cystic Fibrosis
Drug: Placebo Oral capsule
Drug: Sildenafil 40mg oral capsule
Primary Outcome(s)
6 Minute Walk Distance (6MWD) [Time Frame: Change in distance walked between week 1 and week 12.]
Secondary Outcome(s)
Cardiac strain [Time Frame: Change in cardiac strain between weeks 1 and 12]
CFQ-R respiratory domain score [Time Frame: Quality of life assessed at weeks 1 and 12.]
Flow-Mediated Dilation (FMD) [Time Frame: Change in FMD between weeks 1 and 12]
Skeletal muscle function [Time Frame: Change in skeletal muscle function between weeks 1 and 12]
Secondary ID(s)
Sildenafil Exercise
Source(s) of Monetary Support
Please refer to primary and secondary sponsors
Secondary Sponsor(s)
Augusta University
Cystic Fibrosis Foundation
Ethics review
Results available:
Date Posted:
Date Completed:
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