MSD K.K. Receives Manufacturing and Marketing Approval of LYFNUA Tablets, World's First Selective P2X3 Receptor Antagonist for the Treatment of Chronic Cough

MSD K.K. (head office: Chiyoda-ku, Tokyo; Representative Director and President: Kyle Tattle; “MSD”) received on January 20 approval in Japan to manufacture and market Lyfnua® Tablets 45 mg (gefapixant citrate), a selective P2X3 receptor antagonist for the treatment of cough. 

Lyfnua® Tablets will be distributed solely by KYORIN Pharmaceutical Co., Ltd. (head office: Chiyoda-ku, Tokyo; President and CEO: Shigeru Ogihara; "KYORIN"), a subsidiary of KYORIN Holdings, Inc. (head office: Chiyoda-ku, Tokyo; President and CEO: Yutaka Ogihara), under an exclusive distribution agreement with MSD's affiliate company.

As the world's first approved selective P2X3 receptor antagonist, Lyfnua® Tablets inhibit extracellular ATP signaling via P2X3 receptors found on vagal C fibers in the airway and reduce sensory nerve activation and cough. It is indicated for refractory chronic cough.

MSD will continue to develop innovative medicines and vaccines that address unmet medical needs and invent for life. 

KYORIN will expand its product portfolio in its strategic respiratory field by exclusively distributing Lyfnua® Tablets, aiming to further increase its presence in this area and contribute to the treatment of chronic cough. 

Lyfnua® Tablets 45 mg, selective P2X3 receptor antagonist for the treatment of cough


Trade name


Lyfnua® Tablets 45 mg






Generic name


Gefapixant citrate








Refractory chronic cough








Normally for adults, 45 mg of gefapixant is administered orally


twice daily.











Application date

February 26, 2021






Approved date


January 20, 2022