Morphine for Refractory Dyspnea in Interstitial Lung Disease: A Phase I Study (JORTC-PAL 05)

Background: Dyspnea is common in interstitial lung disease (ILD) patients and often refractory to conventional treatment. Little is known regarding the safety of systemic morphine in ILD patients. Objective: The objective of this study is to evaluate the safety of a single subcutaneous morphine injection and to determine the recommended dose of morphine for alleviating dyspnea in ILD patients. Design: We conducted a dose-escalation Phase I study for investigating the recommended dose of a single subcutaneous morphine injection to alleviate dyspnea in ILD patients. Setting/Subjects: Eligible subjects were ILD inpatients with dyspnea at rest who were refractory to conventional dyspnea treatment. The morphine doses used were 1 mg and 2 mg in cohort 1 and cohort 2, respectively. The primary endpoint was dose-limiting toxicity, which was defined as (1) respiratory depression, that is, 30% reduction of respiratory rate and 10 Torr increase of PaCO ₂ compared with baseline; (2) hypotension, that is, 20% reduction of systemic blood pressure compared with baseline and presentation of hypotension-related symptoms; or (3) grade 3, 4, or 5 treatment-emergent adverse events graded by Common Terminology Criteria for Adverse Events (version 4). Results: A total of six patients were enrolled, with three patients each in cohorts 1 and 2. No dose-limiting toxicities were observed; three patients experienced worsened somnolence, but no patients experienced sedation. Conclusion: We conclude that 2 mg of morphine has a tolerable safety profile in ILD patients with dyspnea, and can be tested in further clinical trials.