The Role of Substance P on Perception of Breathlessness During Resistive Load Breathing

The Role of Substance P on Perception of Breathlessness

Substance P is released from sensory nerves and transmits pain information into the central nervous system. As pain and dyspnea share many characteristics, including similar neurological pathways, it is possible that substance P may contribute to the sensation of dyspnea. The hypothesis of the study is that patients with chronic obstructive pulmonary disease (COPD) will provide lower ratings of breathlessness during resistive load breathing with oral aprepitant, a medication that blocks the activity of substance P, compared with placebo.

Inclusion Criteria:

• 50 years of age or older
• diagnosis of COPD
• former smoker > 10 pack-years
• clinical diagnosis of chronic bronchitis
• post-bronchodilator forced expiratory volume in one second (FEV1) 30 - 80% predicted
• FEV1/forced vital capacity ratio less than or equal to 70%

Exclusion Criteria:

• current smoker
• pregnant women
• concomitant disease that might interfere with study procedures
• peripheral vascular disease or cold hypersensitivity
• drugs that might interfere with aprepitant