** Shares of drugmaker United Therapeutics UTHR.O down 3.5% at $345 premarket
** Co posts quarterly adj profit of $6.19 per share, missing analysts' estimates of $6.31 per share, according to data compiled by LSEG
** However, co's Q4 revenue came in at $735.9 million on sales of its lung disorder inhaled-drug Tyvaso, slightly above estimates of $734.7 million
** Brokerage Leerink Partners says it appears that Tyvaso was not quite able to buck seasonal trends this quarter unlike a year ago
** The stock has risen ~60% in the last 12 months
(Reporting by Siddhi Mahatole)
((Siddhiprabhanjan.mahatole@thomsonreuters.com))