This is a phase 2b, randomized, double-blind, placebo-controlled study investigating the efficacy, safety, and tolerability of Taplucainium Inhalation Powder (NOC-110) once daily in adults with refractory or unexplained chronic cough.

Approximately 455 participants will take part in the study. It is anticipated that up to 1264 participants will be screened. Participation will be approximately 13 weeks.

Inclusion Criteria:

• Refractory or unexplained chronic cough for ≥ 12 months.
• Women of childbearing potential agree to follow the protocol specified contraceptive - guidance during the study.
• Males who are not vasectomized must agree to use the contraceptive methods defined in the protocol.
• Able to provide Informed Consent.

Exclusion Criteria:

• Previous exposure to taplucainium (formerly NTX-1175) or known allergy or hypersensitivity to taplucainium, its excipients/metabolites, or related compounds.
• Participants who are currently participating in another drug or device clinical study
• Participants who have participated in an Acute or Chronic Cough investigational study within 60 days before the start of the Screening.
• Current diagnosis of chronic obstructive pulmonary disease, bronchiectasis, unexplained pulmonary fibrosis, hemoptysis, bronchial asthma, or other pulmonary disease.
• Respiratory tract infection within 4 weeks of Screening or during screening period.
• Any female who is pregnant or lactating or wishing to become pregnant.
• Donation of > 1 Unit (450 milliliter or more) of blood within 60 days prior to the first dosing.
• Alcohol or drug use disorder within the past 2 years.
• Current smoker/vaper or individuals who have given up smoking within the past 6 months of screening, and/or those with >20 pack-year smoking history.
• Current opiate/opioid use or medical history of opiate/opioid use disorder.
• History of concurrent malignancy or recurrence of malignancy in the last 2 years.
• Body Mass Index of ≥40 kg/m2.
• Positive results for human immunodeficiency virus, hepatitis B, or hepatitis C virus.
• Unable to refrain from the use of medications and treatments that can impact cough during the study.
• Have clinically significant history or evidence of poorly controlled cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, neurological, immunological, or psychiatric disorder(s).