Safety and Efficacy of Sildenafil in Cystic Fibrosis (CF) Lung Disease

May 13, 2026 updated by: Jennifer Taylor-Cousar, National Jewish Health

The Role of Phosphodiesterase Inhibitors in CF Lung Disease

The purpose of this study is to determine whether sildenafil can decrease inflammation in CF lung 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 study is an open-label study that examines the use of sildenafil (Revatio) in clinically stable patients with mild to moderate CF lung disease. The length of participation for each subject will be approximately 10 weeks, and will consist of a screening visit, a study visit for initiation of study drug if subject qualifies, interim visits to escalate drug dose, obtain drug levels, review concomitant medications and assess side effects, a visit at the end of the therapy period (to reassess inflammatory markers, laboratory studies and side effects,) and a follow-up assessment 2 weeks after subject completion.

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.
36

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
  • Phase 1

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

  • United States
    • Colorado
      • Denver, Colorado, United States, 80206
        • National Jewish Health

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 (Child, Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Confirmed diagnosis of CF based on the following criteria:

    • Positive sweat chloride ≥60mEq/liter (by pilocarpine iontophoresis) and/or
    • Genotype with two identifiable mutations consistent with CF, and accompanied by one or more clinical features consistent with the CF phenotype
  • Male or female patients ≥ 12 years of age
  • FEV1 ≥ 50% predicted (Knudson) 31
  • 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
  • Ability to reproducibly perform spirometry (according to ATS criteria)
  • Ability to produce at least 1mL of sputum spontaneously, or be willing to undergo sputum induction
  • Ability to understand and sign a written informed consent or assent and comply with the requirements of the study
  • Chronic bacterial colonization (3 documented positive cultures in the prior 2 years of which at least one was obtained in the 3 months prior to randomization)

Exclusion Criteria:

  • 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
  • Daily use of systemic corticosteroids and/or NSAIDs within 4 weeks of the study or as needed use within 72 hours prior to the screening visit
  • History of significant hepatic (SGOT or SGPT > 3 times the upper limit of normal at screening, documented biliary cirrhosis, or portal hypertension), cardiovascular (history of aortic stenosis, coronary artery disease, pulmonary hypertension with right ventricular systolic pressure >55 mmHg or life-threatening arrhythmia), neurological (history of stroke), hematologic (history of bleeding diathesis), ophthalmologic (history of retinal impairment or non-arteritic ischemic optic neuritis) or renal impairment (creatinine >1.8 mg/dL.)
  • Inability to swallow pills
  • Previous lung transplantation
  • Use of concomitant nitrates, α-blocker, or Ca channel blocker
  • Use of concomitant medications known to be potent inhibitors of CYP3A4 (e.g. ketoconazole, itraconazole, ritonavir, clarithromycin, erythromycin, rifampin)
  • 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
  • Weight less than 40 kg
  • History of sputum or throat swab culture yielding Burkholderia cepacia within 2 years of screening
  • Resting room air oxygen saturation <93%
  • History of migraines

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: Pilot study of systemic sildenafil administration to people with cystic fibrosis
This is a study of sildenafil administration to patients with mild to moderate cystic fibrosis (CF). All subjects will receive oral sildenafil three times per day during the study. Study endpoints will be measured before the treatment period and at the end of the treatment period to evaluate safety, tolerability, pharmacokinetics in people with CF, and surrogate markers of pulmonary function.
Drug: sildenafil
Sildenafil will be given 20mg po tid for 1 week, and then will be give 40mg po tid for 5 weeks.
Other Names:
  • Revatio

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 Sputum Elastase Activity
Time Frame: Baseline and 6 weeks
Exploratory analysis for efficacy of sildenafil on sputum biomarkers of inflammation, including sputum elastase. This measure will indicate whether sildenafil will increase or decrease sputum elastase activity.
Baseline and 6 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 Exhaled Breath Condensate pH
Time Frame: Baseline and 6 weeks
Endogenous airway acidification can be assessed by measuring pH in exhaled breath condensate, a non-invasive measure of response to therapy. This measure will indicate whether sildenafil will improve, worsen, or cause no change in exhaled breath condensate pH.
Baseline and 6 weeks
Change in Cystic Fibrosis Questionnaire - Revised (CFQ-R) Respiratory Domain, Average Unit Change From Baseline to 6 Weeks is Reported
Time Frame: 6 weeks
The CFQ-R is designed to measure CF-specific patient-reported health-related quality of life. It is a validated CF-specific quality of life measure. The CFQ-R Respiratory domain score (scale 0-100 with higher scores indicating better quality of life). This measure will indicate whether sildenafil will improve, worsen, or cause no change in the CFQ-R respiratory domain scores from baseline at 6 weeks.
6 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.
National Jewish Health

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.
Cystic Fibrosis Foundation

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: Jennifer L Taylor-Cousar, MD, National Jewish Health

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.
August 1, 2008

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.
August 1, 2012

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 1, 2012

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).
April 14, 2008

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.
April 15, 2008

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.
April 16, 2008

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.
May 14, 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.
May 13, 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.
May 1, 2026

More Information

Terms related to this study

Keywords

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.
  • 851R14-8510M3

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

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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