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# FDA Punts Merck Cough Drug Data to Panel
- URL: https://www.fdaweb.com/fda-punts-merck-cough-drug-data-to-panel/
- Published: 2023-11-15T12:00:00.000Z
- Updated: 2026-09-14T14:16:17.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5155796

FDA reviewers say that making an assessment on the clinical meaning of “complicated” data presentations in a Merck NDA resubmission for chronic cough medicine gefapixant is a challenge and will be submitted to an 11/17 Pulmonary-Allergy Drugs Advisory Committee meeting for discussion. An earlier NDA was issued an FDA complete response letter 1/2022\. The resubmission included additional analyses and information related to the cough counting system that was used to assess efficacy.

Because of the complicated data presentations (i.e., log transformation, geometric mean ratio, relative reduction) in the resubmission, reviewers conducted a post hoc analysis of the absolute cough frequency, “a more intuitive expression of the primary endpoint, which revealed small differences between treatment groups in the median cough frequency…,” an agency [briefing document ](https://www.fda.gov/media/173850/download?ref=fdaweb.com)released in advance on the panel meeting says.

In the FDA-conducted analysis, the two pivotal trials for gefapixant showed “baseline mean and median cough frequencies were roughly 20-30 coughs per hour,” the reviewers say. “We question if gefapixant treatment, resulting in a reduction beyond the high placebo response of approximately one to two coughs per hour, results in a benefit that is perceptible to patients.”

FDA says the panel members will be asked to discuss the clinical meaningfulness of the reduction in cough frequency with gefapixant relative to placebo.

Merck says that a refractory chronic cough is one that persists despite appropriate treatment of underlying conditions and an unexplained chronic cough is one where the underlying cause cannot be identified despite a thorough evaluation. Gefapixant is considered an orally administered selective P2X3 receptor antagonist.

P2X3 receptors are one of the receptor types found on sensory nerve fibers, predominantly C fibers, in the airway lining, according to the company. “Chemical stimuli, including adenosine triphosphate (ATP), can be released from airway lining cells due to airway inflammation, irritation and mechanical stress/injury,” it says. “The inhibition of binding of extracellular ATP to P2X3 receptors is thought to reduce sensory nerve activation and, subsequently, cough.”