Opioids for Refractory Breathlessness in Chronic Obstructive Pulmonary Disease

Breathlessness, the sensation of breathing discomfort, is a major problem in people with chronic obstructive pulmonary disease (COPD). Breathlessness that persists despite optimal management of the underlying disease(s) is said to be refractory. Preliminary evidence suggests that a small, regular dose of morphine helps to reduce safely the sensation of breathlessness. However, this research on morphine for breathlessness has not defined the best way to adjust the dose of the medication, or refined which people are most likely to have benefit, no response or side effects. This is a randomized, double-blind phase III trial in people with COPD and significant refractory breathlessness, which will explore several important questions: * Are regular, low dose opioids (morphine) at four possible doses over 3 weeks more effective than placebo medication (containing no active ingredient) at improving breathlessness? * Does the medication have any effect on daily activity, breathlessness, and quality of life? * What are the common side effects of this intervention? * Does the benefit from the drug outweigh the side effects it produces? * Are there specific characteristics of people who are more likely to receive benefit from sustained release morphine? Participants will be allocated to receive three weeks of morphine sulfate (and laxative, docusate with senna), or placebo (and placebo laxative). The dose of morphine may be increased each week for weeks two and three. All medicines will appear the same (blinded) and neither the doctor nor the participant will know which medication the participant is receiving. Participants will have a medical interview, physical examination to collect some general health information, and baseline measurements including; daily activity, symptoms, and quality of life. A small amount of blood may be required to check eligibility. Further blood samples may be taken at week 1 and 3 to enable testing on how individuals respond to opioids, furth