Surface energy changes and their relationship with the dispersibility of salmeterol xinafoate powders for inhalation after storage at high RH

This study investigated the relationship betweent he surface energy of micronized lactose, coarse lactose and salmeterol xinafoate and dispersibility, morphology, and the presence of amorphous domains were determined by inverse gas chromatography, twin stage impinger, scanning electron microscope and dynamic vapour sorption, respectively. The fine particle fraction of mixture decreased significantly in 4 weeks reaching a static level in 3 months. Amorphous content was not detected in the micronized lactose, coarse lactose and salmeterol xinafoate. After conditioning stored samples at ) RH for 2h, no significant difference was observe