Safety And Efficacy Of GSK233705 Plus Salmeterol Compared With 2 Active Comparators And Placebo In Subjects With Chronic Obstructive Pulmonary Disease (COPD)

A Multicentre, Randomised, Partially Blinded, Placebo-controlled, Three-way Crossover, Incomplete Block Design Study to Investigate the Safety, Tolerability, Pharmacodynamics/ Efficacy and Pharmacokinetics of Dual Bronchodilator Therapy With Salmeterol 50µg Twice-daily Plus Two Different Doses of GSK233705B (20 and 50µg Twice-daily), Compared With Placebo, Salmeterol 50µg Twice-daily Alone, and Tiotropium 18µg Once-daily Alone, in Subjects With Chronic Obstructive Pulmonary Disease