Development of a novel method for the continuous blending of carrier-based dry powders for inhalation using a co-rotating twin-screw extruder.

Twin-screw extruders are useful in tuning certain product characteristics due to the ability to greatly modify screw profiles as well as operating parameters. However, their use has not yet been applied to dry powder inhalation. In this study the feasibility of using a twin-screw extruder to blend dry powders for inhalation was assessed. Micronized rifampicin (1%) was used as a model drug with lactose carrier (median size ∼ 44 µm) and 0.4% magnesium stearate as a multi-functional ternary agent. Blend performance was compared with low shear (Turbula®) batch mixing. Similar blend uniformity and aerosol performance was observed, indicating the twin-screw extruder successfully functions as a mixer for dry powders for inhalation. The ability to utilize the twin-screw extruder as a continuous mixer leads to new opportunities in the continuous manufacturing of powders for inhalation.