The purpose of this randomized, placebo-controlled (Phase II) study will be to further evaluate the effects of oral glutathione on growth in children with CF.

a prospective, multi-center, randomized, placebocontrolled, double-blind, Phase II clinical trial. Approximately sixty pancreatic insufficient (PI) subjects with CF who are ≥ 2 and < 11 years of age, will be enrolled to receive either L-Glutathione Reduced (GSH) or placebo given orally (tid) for 24 weeks. Each subject will be seen for four study visits: Visit 1 (Screening), Visit 2 (Baseline/Randomization, Day 0), Visit 3 (Week 12) and Visit 4 (Week 24). At Visit 2, subjects will be randomized to receive either active treatment or placebo. Visit 1 and 2 may be combined if subject meets eligibility requirements and a fecal specimen is collected prior to dosing. Safety and clinical outcomes will be assessed throughout the study. Assessment of inflammatory and other bio-markers in blood and fecal specimens will be performed at Visits 2 and 4

Inclusion Criteria:

1. Male or female ≥ 2 and < 11 years of age at Visit 1
2. Documentation of a CF diagnosis as evidenced by the following criteria: Sweat chloride ≥ 60 mEq/L by quantitative pilocarpine iontophoresis test (QPIT) AND Two well-characterized mutations in the cystic fibrosis transmembrane conductive regulator (CFTR) gene
3. Weight-for-age between the 10th and 50th percentiles at Screening (Visit 1) (using the Center for Disease Control (CDC) reference equations)
4. Current chronic use, greater than 8 weeks before Day 0, of pancreatic enzyme replacement therapy (PERT) for management of pancreatic insufficiency
5. Written informed consent (and assent when applicable) obtained from subject or subject's legal representative and ability to comply with the requirements of the study
6. Clinically stable with no significant changes in health status within 2 weeks prior to Day 0

Exclusion Criteria:

• 1. Intestinal obstruction or gastrointestinal surgery within the 6 months prior to Day 0 2. History of diabetes, Crohn's disease, celiac disease, or bowel resection 3. Use of either oral or inhaled GSH or N-acetyl cysteine within the 4 months prior to Screening (Visit 1) 4. Known hypersensitivity to oral glutathione or lactose 5. Initiation of any new chronic therapy (e.g., ibuprofen, hypertonic saline, azithromycin, Pulmozyme, Cayston TOBI Kalydeco,Orkambi, Proton Pump Inhibitor, Histamine H-2 Blocker [PPI/H2-blocker], Miralax® , PERT, dietary supplementation, probiotics) within the 4 weeks prior to Day 0 6. Changes in the amount of proprietary dietary supplement formulas (e.g., Scandishakes, Boost, Pediasure, or homemade formula) given (oral or gastrostomy tube) within the 4 weeks prior to Day 0 7. Use of antibiotics (oral, IV, or inhaled) for acute symptoms within the 2 weeks prior to Day 0 8. Use of oral steroids within the 4 weeks prior to Day 0 9. Active treatment for nontuberculous mycobacteria (NTM) at Day 0 10. Active treatment for allergic bronchopulmonary aspergillosis (ABPA) at Day 0 11. Administration of any investigational drug within the 30 days prior to Day 0 12. Sibling who received study drug as part of this study 13. Presence of a condition or abnormality that in the opinion of the investigator would compromise the safety of the patient or the quality of the data