A Study to Assess the Efficacy of Gefapixant (MK-7264/AF-219), in Participants With Chronic Cough (MK-7264-006)

A Study to Assess the Efficacy of AF-219, a P2X3 Receptor Antagonist, in Subjects With Chronic Cough (EPiCC)

This is a randomised, double-blind, placebo-controlled, crossover, single centre study of gefapixant (AF-219/MK-7264) in participants with idiopathic or treatment resistant chronic cough designed to evaluate the effectiveness of gefapixant in reducing daytime objective cough frequency.

Inclusion Criteria:

• History of cough for more than 8 weeks
• Normal chest radiograph
• Idiopathic or treatment resistant cough (idiopathic defined as a cough for which no objective evidence of an underlying trigger can be determined after investigation or a cough that is unresponsive to 8 weeks of targeted treatment for identified underlying triggers including reflux disease, asthma and post-nasal drip [treatment-resistant]).

Exclusion Criteria:

• Current smoker
• Individuals who have given up smoking within the past 6 months, or those with >20 pack-year smoking history
• Treatment with an angiotensin-converting-enzyme inhibitor (ACE-inhibitor) as the potential cause of a participant's cough, or requiring treatment with an ACE-inhibitor during the study or within 4 weeks prior to Day 0
• Forced Expiratory Volume (FEV1)/Forced Vital Capacity (FVC) <60%