High shear mixing of lactose and salmeterol xinafoate dry powder blends: biopharmaceutic and aerodynamic performances

This work aimed to investigate the effect of a high shear mixer on the biopharmaceutics and aerodynamic performances of salmeterol xinafoate/lactose blends for inhalation. The influence of mixing energy during blending on powder bulk properties, aerosolisation and in vitro dissolution rate of drug was studied. There was a clear dependence of the blends bulk characteristics on the mixing rate and time that affected the emitted dose. The fine particle dose or respirable fraction of salmeterol xinafoate was favored by the mixing intensity leading to the disaggregation of the drug particles. An important dependence of the extra-fine drug particles on the mixing conditions was determined. The effective dispersion on the carrier particles of the salmeterol xinafoate improved the dissolution rate of the drug from the blend. This was due to the drug particle size distribution in the blend. When the fine particle dose of different blends was dissolved, no differences among the dissolution rates were observed.