Anthony J. Hickey, Erik S. Pena, Sara E. Maloney
The design of pharmaceutical inhalation aerosol particles is determined by the intended application. Efficiency and reproducibility of dose delivery must be considered in terms of the biological determinants of pulmonary drug delivery and the physicochemical and technical determinants of the therapeutic formulation and device. The biological considerations can be divided into disease, pulmonary target, and lung physiology and anatomy, which dictate pulmonary function and lung deposition of aerosols. The physicochemical properties of the drug, alongside those of added excipients, are the foundation of particle structure. Effective delivery of a particle formulation requires an appropriate device, the technical aspects of which influence aerosolization of the formulation. The interface between the biological, formulation, and technical considerations relates to drug potency, target dose, and the ability to modulate efficacy through pharmacokinetics of disposition. Altogether, these determinants must be considered for efficient delivery to the respiratory tract.