It has been estimated that chronic cough affects up to 10% of the US population, with one in five of them getting no benefit from current treatments such as opioids and corticosteroids.

Merck filed for approval of gefapixant in March 2021 on the strength of a pair of phase 3 trials – COUGH-1 and COUGH-2 – which found that the drug reduced 24-hour cough frequency by 18% and 15 ...