Inhaled Fentanyl Citrate Improves Exercise Endurance During High-Intensity Constant Work Rate Cycle Exercise in Chronic Obstructive Pulmonary Disease

Single-dose inhalation of fentanyl citrate was associated with significant and potentially clinically important improvements in exercise tolerance in COPD. These improvements were accompanied by a delay in the onset of intolerable dyspnea during exercise near the limits of tolerance.