Sildenafil for Chronic Obstructive Pulmonary Disease

Patients with chronic obstructive pulmonary disease (COPD) suffer from impaired exercise capacity and quality-of-life, largely related to shortness of breath. Many of the therapies currently available for COPD are aimed at improving these factors. Exercise capacity is limited in part by high blood pressure in the blood vessels in the lungs. Sildenafil, also known as Viagra, is an FDA-approved therapy for male erectile dysfunction. One of its effects is to relax (or open) the lung vessels, thereby lowering the blood pressure in the lungs. We hypothesize that sildenafil will result in an improvement in exercise capacity, quality-of-life, and shortness of breath.

Enrolled subjects will receive sildenafil or placebo for 4 weeks followed by exercise tests, breathing tests, and administration of quality-of-life questionnaires. Subjects will then receive placebo or sildenafil (whichever one they did not receive for the first 4 weeks) for another 4 weeks, followed by the same testing.

• Pulmonary Disease, Chronic Obstructive
• Emphysema

• Drug: sildenafil citrate
  sildenafil citrate 25 mg by mouth thrice daily (po tid)
• Drug: Placebo
  25 mg po tid

• Active Comparator: Sildenafil / Placebo
  Sildenafil first, followed by washout, followed by placebo
  Interventions:

  • Drug: sildenafil citrate
  • Drug: Placebo
• Placebo Comparator: Placebo / Sildenafil
  Placebo first, followed by washout, followed by Sildenafil
  Interventions:

  • Drug: sildenafil citrate
  • Drug: Placebo

Inclusion Criteria:

• Clinical diagnosis of chronic obstructive pulmonary disease (COPD) or emphysema
• FEV1/FVC ratio < 70%
• FEV1 < 80%
• Stable medication regimen

Exclusion Criteria:

• COPD exacerbation or hospitalization in the past 3 months
• Heart disease
• Contraindication to sildenafil
• Unrelated lung disease
• Inability to walk or pedal on a stationary bike
• Pregnancy or breast-feeding
• Pulmonary hypertension at rest