To evaluate the systemic exposure of treprostinil after inhaled administration in subjects with idiopathic pulmonary fibrosis (IPF)
1. Subject gives voluntary informed consent to participate in the substudy
2. Subject has been on a stable dose of inhaled treprostinil in RIN-PF-302 for at least 30 days and is receiving at least 9 breaths (54 mcg) 4 times daily (QID).
3. Subject is able to administer study drug on the day of the PK substudy visit in the clinic and at least 4 hours after the previous dose of study drug.
1. Subject is pregnant or lactating.
2. In the opinion of the Investigator, enrollment in RIN-PF-302 would represent a risk to the subject’s overall health.
The second visit will be 4 weeks after the first and then the next visit will be 8 weeks after the second. Then, all visits will be 12 weeks apart until the study has enrolled enough patients and they sponsor determines that the study may end. Efficacy assessments will include spirometry (forced expiratory volume in 1 second [FEV1] and forced vital capacity [FVC]), time to clinical worsening, time to first acute exacerbation of IPF, overall survival, King's Brief Interstitial Lung Disease (K-BILD) Questionnaire, plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration, supplemental oxygen use, and diffusion capacity of lungs for carbon monoxide (DLCO). Safety assessments will include monitoring for the development of AEs/SAEs, vital signs, clinical laboratory parameters, and electrocardiogram (ECG) parameters. In addition, up to 24 eligible subjects may participate in a PK substudy to evaluate the systemic exposure of treprostinil after inhaled administration.