Sildenafil for Chronic Obstructive Pulmonary Disease: A Randomized Crossover Trial

Rationale: Pulmonary hypertension with exercise is common in chronic obstructive pulmonary disease (COPD) and may contribute to exercise limitation in this disease. We aimed to determine the effects of treatment with sildenafil on exercise capacity in patients with COPD and emphysema. Methods: We performed a randomized, double-blind, placebo-controlled 2-period crossover trial of sildenafil thrice daily in ten adults with COPD and emphysema on CT scan without pulmonary hypertension. We randomized study participants to 4 weeks of sildenafil (or placebo) followed by a 1-week washout and then 4 weeks of placebo (or sildenafil). The 2 primary outcomes were the 6-minute walk distance and oxygen consumption at peak exercise. Results: Sildenafil had no effect on 6-minute walk distance (placebo-corrected difference = -7.8 m, 95% confidence interval, -23.2 to 7.5 m, p = 0.35) or oxygen consumption at peak exercise (placebo-corrected difference = -0.1 ml/kg/min, 95% confidence interval -2.1 to 1.8 ml/kg/min, p = 0.89). Sildenafil increased the alveolar-arterial oxygen gradient (p = 0.02), worsened symptoms (p = 0.04), and decreased quality-of-life (p = 0.03). Adverse events were more frequent while receiving sildenafil (p = 0.005). Conclusions: Routine sildenafil administration did not have a beneficial effect on exercise capacity in patients with COPD and emphysema without pulmonary hypertension. Sildenafil significantly worsened gas exchange at rest and quality of life. (clinicaltrials.govNCT00104637).