Table II.

Characteristics of Inhalable Nanoparticle-based Dry Powder Formulations

	Nano-embedded microparticles	Nanoagglomerate microparticles	Nanoparticle-carrier system
Morphology	Spherical	Hollow/porous	Spherical
Nanoparticle dispersion mechanism in respiratory tract	Dissolution of bulking/shell-forming agent	Dissolution of excipient bridges between agglomerated nanoparticles	Physical detachment of nanoparticles from carriers during inhalation
Production method	Spray drying/(spray) freeze drying of nanosuspension with bulking/shell-forming agent(s)	Spray drying/(spray) freeze drying of nanosuspension with protectant(s)	Blending/coating of dried nanoparticles with micron-sized carrier particles
Drug loading	Low	High	Very low
Flow rate dependence	Low	Low	High