** Shares of Liquidia LQDA.O fall ~5.7% to $15.01
** The U.S. FDA approved Merck's MRK.N treatment for
adults with pulmonary arterial hypertension (PAH), late on
Tuesday
** Liquidia has said the FDA was still reviewing its PAH
inhaled drug yutrepia, decision on which was due on Jan. 24
** Last month, United Therapeutics UTHR.O said it had
filed a case with the FDA alleging that due procedure was not
followed in allowing rival Liquidia's application for the drug
** PAH is caused by a constriction of arteries in the lungs,
leading to high blood pressure and symptoms such as shortness of
breath, chest pain and dizziness
** LQDA stock more than doubled in the last 12 months
(Reporting by Christy Santhosh)
((Christy.Santhosh@thomsonreuters.com))