This study will evaluate the impact Nintedanib Solution for Inhalation (AP02) has on lung function and key measures of fibrosis in adult patients with idiopathic pulmonary fibrosis (IPF) as well as assess its safety and tolerability.

Adults 40 years of age or older with IPF who meet the inclusion and exclusion criteria can participate in this study if they are not currently on treatment for IPF, and if treated with oral nintedanib or pirfenidone, have stopped the medication for at least 3 months.

Researchers will compare two different doses of AP02 to a placebo (a look-alike substance that contains no drug) to see if AP02 works to treat IPF. Participants are put into 1 of 3 groups randomly, which means by chance and will take AP02 or a placebo two times every day for 12 weeks by using a nebulizer, which is a device that provides medicine to the lungs via inhalation