** Shares of drug developer Aquestive Therapeutics AQST.O fall 44% to $3.49 premarket

** Co says it received a letter from the U.S. FDA highlighting issues with its new allergy treatment, Anaphylm

** FDA raised concerns delaying talks on Anaphylm's labeling and marketing, per co

** AQST's Anaphylm is a dissolvable film with epinephrine for severe allergic reactions - AQST

** The FDA is expected to make a decision on Anaphylm by January 31, the scheduled action date

** Co says if approved, it would be first oral alternative to epinephrine auto-injectors

** As of last close, stock up ~81% over the past year

(Reporting by Sahil Pandey in Bengaluru)

((Sahil.Pandey@thomsonreuters.com))