A Two-part study to learn the amount of polymyxin E1 in the body over time formed after a single inhaled dose of colistimethate sodium (CMS) in healthy adults (Part 1) and after single inhaled and vein-infused doses of CMS in adults with non‑cystic fibrosis bronchiectasis (NCFB) (Part 2)

Non-cystic fibrosis bronchiectasis is a long-term lung condition where the airways become widened and scarred. This damage makes it harder for the lungs to clear mucus, creating an environment where bacteria can grow and cause repeated chest infections. To manage these flare-ups and protect lung function, doctors often rely on specialised antibiotics.

One important antibiotic used for difficult-to-treat infections is colistimethate sodium, often shortened to CMS. Once it enters the body, CMS gradually converts into its active form, polymyxin E1, which actively attacks harmful bacteria. This trial is designed to track how much of this active medicine is formed, how quickly it travels through the bloodstream, and how long it stays in the body.

The study is divided into two parts. In the first part, healthy adult volunteers will breathe in a single dose of the medicine to establish a baseline of how the drug behaves. In the second part, adults living with bronchiectasis will receive the medicine in two different ways: once inhaled directly into the lungs and once given through a drip into a vein.

Because this is an early pharmacology (Phase 1) trial, the goal is not to cure lung disease, but rather to gather precise scientific data. By learning how different people process the drug, researchers hope to guide safer and more effective dosing for patients who need it most.