UPDATE 1-Theravance asthma therapy found safe in mid-stage trial

* Says drug well-tolerated in asthma patients

* Says incidence of adverse events comparable to placebo

* Says no significant abnormalities in vital signs

May 19 (Reuters) - Theravance Inc THRX.O said data presented by partner GlaxoSmithKline GSK.L from a mid-stage trial showed that their experimental asthma treatment was well-tolerated in patients, with no significant adverse effects.

Vilanterol trifenatate, coded GW642444M, when taken in combination with an inhaled steroid, facilitated rapid and prolonged airflow in patients with mild to moderate persistent asthma over 24 hours after taking the drug, Theravance said in a regulatory filing.

Theravance said incidence and severity of adverse events in patients treated with the drug were comparable to those treated with a dummy drug.

Single doses of the drug did not show any clinically significant abnormalities in vital signs in asthma patients, suggesting potential for a daily dosage, the company said.

Shares of Theravance closed at $14.23 Wednesday on Nasdaq. (Reporting by Krishnakali Sengupta in Bangalore; Editing by Roshni Menon)