Refractory Chronic Cough Improvement Via NAL ER (RIVER)

Key Inclusion Criteria:

• Diagnosis of refractory chronic cough (RCC) for at least one year

• Chest radiograph or CT of thorax within 24 months or during screening notdemonstrating any significant abnormalities contributing to RCC

Exclusion Criteria:

• Diagnosis of sleep apnea

• Respiratory tract infection within 6 weeks of Baseline

• History of bronchiectasis, COPD, or IPF

• History of uncontrolled asthma

• Current smokers/vapers, quit smoking with <=12 months, using nicotine supplements,or history of >=20 pack years

• History of major psychiatric disorder

• History of substance abuse

• Pregnant or lactating females

• Known intolerance to opioids

• Abnormal kidney or liver functions based on Screening lab results.

• Known hypersensitivity to nalbuphine or to NAL ER excipients

• Previous participation in a nalbuphine ER clinical study

• Use of opiates, benzodiazepines, or MAOIs within 14 days of Baseline

• Use of pregabalin, gabapentin, thalidomide for treatment of cough within 14 days ofBaseline

• Use of ACE inhibitors within 12 weeks of Baseline

• 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 QTprolongation but not clearly associated with Torsade de Pointes within 4 weeks ofscreening.

• Use of unstable doses of cough suppressants within 14 days of Baseline

• Use of unstable doses of medications that affect serotonergic neurotransmission thatmay cause serotonin syndrome with opioids within14 days of Baseline

• Use of unstable doses of P450 isozyme inhibitors/inducers within 14 days of Baseline

Other protocol defined inclusion/exclusion criteria may apply.