PK, Safety and Preliminary Efficacy Study of Montelukast in Critically Ill Infants With Developing Bronchopulmonary Dysplasia

Inclusion Criteria 1. Documented informed consent from parent or guardian, prior to study activities 2. Receiving mechanical ventilation \[high frequency or conventional\] and requiring supplemental oxygen (FiO2 ≥ 30%) at time of randomization 3. \<28 weeks' gestational age and \<1000 g bodyweight at birth 4. 7 to 28 (inclusive) days postnatal age at the time of first study drug dose 5. Able to tolerate 5 mL of enteral volume Exclusion Criteria 1. Previous enrollment and dosing in the current PRISM study (NICHD-2023-MON01) 2. Previous exposure to montelukast within 7 days prior to randomization 3. Known allergy to montelukast 4. PI deems infant - prior to enrollment - is not expected to survive 5. Has a disease complication that would preclude safe participation of the participant 6. Increased respiratory support due to intercurrent illness (e.g., sepsis, necrotizing enterocolitis, etc.). Infants should be excluded from the study until after resolution of the acute event 7. Congenital lung and diaphragmatic malformations