This clinical trial is focused on studying a lung condition known as Progressive Pulmonary Fibrosis (PPF). PPF is a disease where the lungs become scarred over time, making it difficult to breathe. The study will evaluate a treatment called Pirfenidone Solution for Inhalation, also referred to as AP01. This treatment is administered through a device called the eFlow Nebuliser System, which helps deliver the medication directly into the lungs in the form of a mist.

The purpose of the study is to assess the safety and effectiveness of AP01 in people with PPF. Participants in the study will be randomly assigned to receive either the AP01 treatment or a placebo, which looks like the treatment but does not contain the active medication. The study will last for 52 weeks, during which participants will have regular check-ups to monitor their lung function and overall health.

Throughout the study, the main focus will be on changes in lung function, specifically measuring something called forced vital capacity (FVC), which is a way to assess how well the lungs are working. Additionally, the study will look at the quality of life of participants and any changes in lung scarring using a special imaging method called high-resolution computed tomography (HRCT). The goal is to understand how AP01 might help improve breathing and slow down the progression of lung scarring in people with PPF.