Overview An 8-Week Refractory Chronic Cough Study (MK-7264-021) Status: Completed Trial end date: 2016-05-18 Target enrollment: Participant gender: Summary This was an 8-week randomized, parallel, double-blind, placebo-controlled study of gefapixant (AF-219) in participants with refractory chronic cough. Phase: Phase 2 Details Lead Sponsor: Afferent Pharmaceuticals, Inc.