** Shares of drug developer Milestone Pharmaceuticals MIST.O fall 8% to 73 cents, extending decline to third day

** Brokerage TD Cowen downgrades MIST to "hold" from "buy", removes PT

** Cites etripamil's regulatory and commercial timing uncertainty

** "The lack of clarity on regulatory timelines puts additional strain on the company's limited capital," says brokerage

** MIST shares fell ~61% on Friday after the U.S. FDA declined to approve its nasal spray, Cardamyst, to treat a type of heart condition

** Including session moves, MIST stock down ~69% YTD compared to ~5% decline in the S&P 500 index .SPX

(Reporting by Ateev Bhandari in Bengaluru)

((Ateev.Bhandari@thomsonreuters.com;))