Requiring invasive or noninvasive respiratory support (e.g., mechanical ventilation, CPAP)

Clinically unstable (i.e. unable to maintain SpO2 between 90-95 % , escalating respiratory support in the past 24 hours)

Major congenital anomaly (chromosomal, renal, cardiac, hepatic, neurologic or pulmonary malformations)

Significant cardiac disorder (i.e., pulmonary hypertension)

History of major surgical procedure

Any condition that would preclude receiving study drug or performing any study-related procedures

Participation in any other investigational drug study

History of hypersensitivity or intolerance to cromolyn sodium

Open-label Study of Inhaled RVT-1601 in Preterm Infants