Back to basics: The development of a simple, homogenous, two-component dry-powder inhaler formulation for the delivery of budesonide using miscible vinyl polymers

It was hypothesised that formulating a dry-powder inhaler (DPI) using a refined, smooth grade of lactose, without fines and a polymer coated drug microparticle should produce an homogeneous formulation in which aerosolisation behaviour could be modified. Hence, the aim of this study was to develop a simple two component polymer coated-budesonide/lactose blend in which the drug microparticle adhesive forces could be optimised by modifying the drug coating in order to improve aerosolisation from a DPI. Budesonide microparticles (1.83 +/- 0.03 mu m) were coated with the vinyl polymers by adsorption and then spray-dried. The drug was blended with three different types of lactose, checked for uniformity of mixing and loaded into Pulvinal ((R)) devices. The median volume particle size of all but one of the polymer coated microparticles remained below 4 mu m after spray-drying and the content uniformity for all the blends > 96%. Coating the budesonide with 0.01% poly(vinyl alcohol) increased the fine particle fraction (FPF) in the next generation impactor (NGI) from 29.1 +/- 0.7% to 52.8 +/- 1.0% and reduced the force of adhesion from 410 +/- 182 to 241 +/- 82 nN with smooth lactose. This illustrates that vinyl polymers could effectively modify adhesive interactions without the need for ternary components such as fines. (C) 2007 Wiley-Liss, Inc