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Oral Sildenafil for Exercise Capacity, Dyspnea and Cardiopulmonary Function in COPD

Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a condition characterized by airway obstruction. Patients with COPD experience significant shortness of breath on exertion. The mechanisms responsible for shortness of breath on exertion are well understood in moderate and severe COPD, but, are poorly understood in mild COPD where symptoms appear disproportionate to the degree of airway obstruction.

Mild COPD patients show an exaggerated breathing response to exercise, determined by the breathing response to carbon dioxide production (V̇E/V̇CO2). Recent work suggests that the increased V̇E/V̇CO2 during exercise in mild COPD is secondary to increased deadspace (i.e. lung regions with ventilation but no perfusion) and/or ventilation/perfusion (V̇A/Q) inequality (poor matching of ventilation to perfusion). Researchers have proposed that the increased deadspace or V̇A/Q inequality is secondary to pulmonary vascular dysfunction and hypoperfusion of the pulmonary capillaries.

Recently, we have shown that inhaled nitric oxide, a potent dilator of pulmonary vasculature, reduces shortness of breath and V̇E/V̇CO2, and improves exercise capacity in mild COPD. This preliminary finding suggests that pulmonary vascular dysfunction is an important contributor to exercise intolerance in mild COPD. Here, we aim to test whether sildenafil, an oral pulmonary vasodilator, can improve exercise tolerance and shortness of breath in mild COPD.

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Participation Requirements

  • Sex:

    ALL

  • Eligible Ages:

    40 to 80

Participation Criteria

Inclusion Criteria:

Participants will have COPD as defined as:

1. Post bronchodilator Forced Expiratory Volume in one second (FEV1) to Forced Vital Capacity (FVC) ratio (FEV1/FVC) below the lower limit of normal
2. FEV1 \>30% of predicted (lower limit of GOLD severe COPD classification)

COPD Free Controls will have:

1. No diagnosis of COPD
2. Post bronchodilator Forced Expiratory Volume in one second (FEV1) to Forced Vital Capacity (FVC) ratio (FEV1/FVC) above the lower limit of normal
3. FEV1 \>80% of predicted

Exclusion Criteria:

1. Absolute contraindication to exercise testing or an orthopedic condition that may limit exercise testing.
2. Pre-existing cardiac conditions (heart failure, congenital heart defect, valvular disease) that may limit exercise testing
3. A diagnosis of pulmonary hypertension preceding COPD
4. Current phosphodiesterase type-5 inhibitor, nitrate, opioid, azole antifungal, macrolide antibiotic, protease inhibitor, alpha blocker, riociguat, mifepristone or rifamycin use.
5. Pregnancy or lactation.
6. Women of childbearing potential must be willing to use an acceptable method of contraception to avoid pregnancy throughout the study. Acceptable methods of contraception include tubal ligation, oral contraceptive, barrier methods (intra-uterine device, diaphragm, female condom, male condom). Abstinence is an acceptable form of contraception, only insofar as patients agree to use another acceptable method of birth control, preferably a barrier method, if they become sexually active.
7. Postmenopausal female participants must be amenorrheic for ≥12 months.

Study Location

Clinical Physiology Laboratory
Clinical Physiology Laboratory
Edmonton, Alberta
Canada

Contact Study Team

Backup Contact

Michael K Stickland, PhD

[email protected]
780-492-3995
Primary Contact

Desi Fuhr, MSc

[email protected]
780-492-1121
Study Sponsored By
University of Alberta
Participants Required
More Information
Study ID: NCT05061368