21 December 2023 - Merck today announced that the US FDA has issued a complete response letter regarding Merck’s new drug application for gefapixant, an investigational, non-narcotic, oral selective P2X3 receptor antagonist, under development for the treatment of refractory chronic cough or unexplained chronic cough in adults. 

In the complete response letter, the FDA concluded that Merck’s application did not meet substantial evidence of effectiveness for treating refractory chronic cough or unexplained chronic cough.

Read Merck press release