Inhaled pirfenidone is a promising and well-tolerated treatment for idiopathic pulmonary fibrosis (IPF), according to a study published in Thorax.

AP01 is an inhaled formulation of pirfenidone designed to expedite delivery to lung tissue; crucially, it also aims to decrease systemic exposure and reduce some of the adverse events associated with the oral formulation of the drug. ATLAS, a randomized, parallel-group, open-label trial conducted from May 2019 to October 2021 in multiple countries, assessed the safety and efficacy of AP01 in patients with IPF. West and colleagues sought to present the results from week 24 (the primary endpoint of the study) as well as those from week 48 for comparison. 

Eligible participants were 40 years of age and above with a diagnosis of IPF according to European Respiratory Society/American Thoracic Society criteria; patients also must not have been taking pirfenidone or nintedanib at the time of enrollment. Those with acute exacerbations requiring hospitalization in the preceding 3 months were excluded. The study enrolled 91 patients. 

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Participants were required to provide laboratory and in-clinic spirometry readings, as well as self-reported outcome measures, once every 4 weeks for 24 weeks, then every 12 weeks until week 72. The primary measurement of interest was the absolute change in predicted forced vital capacity from baseline to week 24. Other measurements of lung health, such as changes in diffusion capacity for carbon monoxide, were also carried out.

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The research team reported that the side effects commonly associated with oral pirfenidone were less frequently reported following the administration of AP01. This suggests that inhaled pirfenidone lessens unnecessary systemic exposure. Meanwhile, forced vital capacity remained stable in patients receiving a dose of 100 mg twice daily. 

IPF is characterized by breathlessness and cough. Its prognosis is poor, with many patients dying within the first 5 years of diagnosis due to respiratory failure or related comorbidities. There are currently 2 approved medications for treating IPF: pirfenidone and nintedanib. Despite their ability to slow disease progression, both drugs are associated with adverse events such as gastrointestinal manifestations, liver enzyme derangement, and photosensitivity. 

“Future studies exploring the potential for fewer adverse effects and improved efficacy compared with current antifibrotics in reducing or slowing progression of fibrosis, ameliorating decline in [forced vital capacity], and meaningfully improving quality of life are warranted,” the authors of the study wrote. 


West A, Chaudhuri N, Barczyk A, et al. Inhaled pirfenidone solution (AP01) for IPF: a randomised, open-label, dose-response trialThorax. Published online March 22, 2023. doi:10.1136/thorax-2022-219391