Morphine: a Novel Intervention to Maximize the Benefits of Exercise Training in Adults With Chronic Lung Disease and Persistent Breathlessness?

Supervised exercise training programs (such as pulmonary rehabilitation) are an integral component of the clinical management of COPD or ILD; a proven intervention for improving symptom burden, quality of life, emotional function, exercise capacity, and risk of hospitalization and death. While both low and high intensity exercise training benefits adults with COPD or ILD, evidence supports that higher intensity exercise training produces relatively greater physiological and symptomatic improvements. High intensity exercise of adequate duration is, however, difficult and unpleasant for people with COPD or ILD due to heightened exertional symptoms, particularly breathlessness.These symptoms persist despite the patient's underlying disease being optimally managed according to evidence-based clinical practice guideline standards.

Low-dose immediate-release oral morphine has recently shown promise as a novel adjunct therapy to reduce exertional breathlessness and increase exercise endurance time in people with advanced chronic lung disease (COPD). The purpose of this randomized, double-blind, placebo-controlled, two-arm pilot study is to further explore the role of low-dose immediate-release oral morphine as an adjunct pharmacotherapy to enable symptomatic adults with advanced COPD or ILD to exercise at higher intensities for longer durations and maximize the psycho-physiological benefits of a 5-week supervised exercise training program.

Adults with a clinical diagnosis of COPD or ILD and chronic breathlessness syndrome will be randomized in a 1:1 ratio to exercise training with oral morphine (ExT+MOR) (n=20; 10 COPD and 10 ILD) or exercise training with placebo (diluted simple syrup) (ExT+PLA) (n=20; 10 COPD and 10 ILD). All eligible participants will complete four assessment visits (Visits 1, 2, 3 and 4) and 15 exercise training (T1-15) sessions. Assessment Visits 1 and 3 will include post-bronchodilator (400 mg Salbutamol) pulmonary function testing and a symptom-limited incremental cardiopulmonary exercise test (CPET) to determine peak power output (PPO). Visits 2 and 4 will include a symptom-limited constant-load CPET at 75% of the PPO determined at Visit 1 and a dual energy x-ray absorptiometry (DEXA) scan to assess body composition. Supervised exercise training will be performed three times per week for five weeks on an electronically braked cycle ergometer, supervised by a trained exercise specialist. Exercise sessions will be individualized based on participants' pre-defined PPO (initial intensity of 60% PPO), and progressed to ensure the participant is exercising at an intensity corresponding to a breathlessness intensity rating of between 3-5 Borg 0-10 category ratio scale (CR10) units and can complete at least 20-min of continuous cycling. Exercise duration will be increased in 5-min intervals up to 40-min. Thereafter, exercise intensity will be increased by 5-15% of baseline PPO.