Clinical Endpoint Bioequivalence Study for Fluticasone Propionate and Salmeterol Xinafoate

The primary objective of this study is to evaluate the clinical bioequivalence of generic fluticasone propionate 100 µg and salmeterol xinafoate 50 µg inhalation powder (test) to Advair Diskus ("Advair") 100/50 (reference) for the treatment of asthma. The secondary objectives of the study are: * To demonstrate statistical superiority of generic fluticasone propionate 100 µg and salmeterol xinafoate 50 µg inhalation powder to placebo. * To demonstrate statistical superiority of Advair 100/50 to placebo. * To investigate the safety and tolerability of fluticasone propionate 100 µg and salmeterol xinafoate 50 µg inhalation powder compared with Advair 100/50 in the target population.