Supercritical Fluid Particle Design of DPI Formulations (Review)

Pulmonary drug delivery (PDD) with dry powder inhaler (DPI) has rapidly developed for the treatment of local and systemic diseases, which targets the delivery of fine drug particles into the deep lung surface by combining technologies of fine drug particle formulation, small dose packaging and suitable inhaler, where by each contributes to the overall aerodynamic performance. The basic requirements of DPI formulation are an excellent aerodynamic performance, including particle size distribution within 1-5 μm, suitable morphology and electrostatic charge, low surface energy, high deposition rate and long shelf life stability. The strategy of DPI formulation is shifting from carrier-based to carrier free, from single drug to drug combination, from microparticles to nanoparticles and from small molecules to biomacromolecules. Making such DPI formulation is a big challenge for conventional pharmaceutical techniques. Fortunately, an emerging technology of supercritical fluid particle design (SCF PD) provides a powerful platform for DPI formulation since it runs single step operation at near ambient temperature to minimize the potential damage of delicate active ingredients and to ensure the consistency of the DPI formulation. Combining with our research experiences in DPI formulation of budesonide and recombinant human insulin, this review focus on the most recent development of DPI formulation using SCF PD technology, which can well control and tune the particle size, morphology and surface properties through different design routes (nanoparticles or microparticles, polymorphic particles, composite particles and bio-drug particles), and hence enable prominent enhancement aerodynamic performance and pulmonary deposition of such inhaled dry powders. Also considered within this review is the progress of the industrialization of SCF PD processes for DPI formulation.