Cough Reduction in IPF With Nalbuphine ER (CORAL)

Inclusion Criteria: Diagnosis of IPF as determined by the Principal Investigator based on ATS/ERS/JRS/ALAT guidelines. Cough Severity Score ≥ 4 on CS-NRS (Cough Severity Numerical Rating Scale) during the Screening period and Baseline. History of chronic cough for at least 8 weeks before screening. SpO2 ≥ 92%, taken after at least 5 minutes in a sitting position, undisturbed and non-stimulated (Saturation of Hemoglobin with Oxygen as Measured by Pulse Oximetry). FVC ≥ 40% predicted of normal - Forced Vital Capacity, as determined by spirometry adhering to ATS/ERS guidelines. DLCO ≥ 25% predicted of normal - Diffusing capacity of the lung for carbon monoxide corrected for hemoglobin, assessed within the last 12 weeks, or at the time of screening. Exclusion Criteria: Currently on continuous oxygen therapy for longer than 16 hours at any level or delivered by any modality. Intermittent oxygen use of any duration over any given 24-hour period is allowed. Inadequate swallow reflex as assessed by the ability to sip 3 fluid oz (or 89 mL) of water without coughing or choking. Upper or lower respiratory tract infection in the last 8 weeks prior to the baseline visit. Clinical history of aspiration pneumonitis. Diagnosis of sleep apnea. Abnormal kidney or liver functions based on Screening lab results. Known hypersensitivity to nalbuphine or to NAL ER excipients History of major psychiatric disorder. History of substance abuse. Significant medical condition or other factors that may interfere with the subject's ability to successfully complete the study. Pregnant or lactating female subject. Known intolerance (gastrointestinal, central nervous system symptoms), hypersensitivity, drug allergy following the use of an opioid drug. Use of opiates is prohibited within 14 days prior to the baseline visit. Use of benzodiazepines are prohibited within 14 days prior to the baseline visit and for the duration of the study. Monoamine oxidase inhibitors (MAOIs) including methylene blue (methylthioninium chloride) and the antibiotic linezolid are prohibited within 14 days prior to the baseline visit and for the duration of the study. Use of oral corticosteroid cough treatment is prohibited within 4 weeks prior to the baseline visit and for the duration of the study. Exposure to any investigational medication, including placebo, is prohibited within 4 weeks prior to the baseline visit and for the duration of the study. Medications prescribed as cough suppressants are prohibited unless on a stable dose 14-days prior to the baseline visit and are expected to remain on that dose for the duration of the study. Use of medications that affect serotonergic neurotransmission and that when used concomitantly with opioids can increase the risk of serotonin syndrome are prohibited unless on a stable dose 14-days prior to the baseline visit and are expected to remain on that dose for the duration of the study. Anti-fibrotic medications are prohibited unless on a stable dose for 8 weeks prior to the baseline visit and are expected to remain on that dose for the duration of the study. Strong inhibitors/inducers of the P450 Isozymes are prohibited unless on a stable dose for 14-days prior to baseline visit and are expected to remain on that dose for the duration of the study. Use of a medication having a "known risk" of Torsade de Pointes (categorized as "KR" on the Credible Meds® website.) 4 weeks prior to Baseline. Use of unstable doses of medications associated with a potential risk of QT prolongation but not clearly associated with Torsade de Pointes within 4 weeks of screening.