Study of Gefapixant (MK-7264) in Adult Japanese Participants With Unexplained or Refractory Chronic Cough (MK-7264-033)

Inclusion Criteria: * Chest radiograph or computed tomography scan of the thorax (within 5 years of Screening/Visit 1 and after the onset of chronic cough) not demonstrating any abnormality considered to be significantly contributing to the chronic cough or any other clinically significant lung disease in the opinion of the principal investigator or the sub-investigator. * Has had chronic cough for ≥ 1 year and a diagnosis of refractory chronic cough or unexplained chronic cough. * For female participants, is a female who is not pregnant, not breastfeeding, not of childbearing potential, or agrees to follow contraceptive guidance * Provides written informed consent and is willing and able to comply with the study protocol (including use of the digital cough recording device and completion of study questionnaires) Exclusion Criteria: * Is a current smoker or has given up smoking within 12 months of Screening, or is a former smoker with a pack-year history \>20 pack-years * Has a history of upper or lower respiratory tract infection or recent clinically significant change in pulmonary status * Has a history of chronic bronchitis * Is currently taking an angiotensin converting enzyme inhibitor (ACEI), or has used an ACEI within 3 months of Screening * Has a history of malignancy ≤5 years * Has a screening systolic blood pressure \>160 millimeters of mercury (mmHg) or a diastolic blood pressure \>90 mm Hg * Has a history of cutaneous adverse drug reaction to sulfonamides with …