Seroxyn ® Acucap is a combination of Salmeterol Xinafoate and Fluticasone Propionate. Salmeterol Xinafoate is a selective, long acting β2 agonist; it attaches to β2 receptors on the smooth muscle cells that surround the airways, causing the muscle cells to relax and opening the airways. Fluticasone Propionate is a synthetic corticosteroid which is a glucocorticoid receptor agonist with mainly potent anti-inflammatory activity.