Dry powder inhalers (DPIs) offer distinct advantages as a means of pulmonary drug delivery and have attracted much attention in the field of pharmaceutical science. DPIs commonly contain micronized drug particles which, because of their cohesiveness and strong propensity to aggregate, have poor aerosolization performance. Thus carriers with a larger particle size are added to address this problem. However, the performance of DPIs is profoundly influenced by the physical properties of the carrier, particularly their particle size, morphology/shape and surface roughness. Because these factors are interdependent, it is difficult to completely understand how they individually influence DPI performance. The purpose of this review is to summarize and illuminate how these factors affect drug-carrier interaction and influence the performance of DPIs.
Keywords: API, active pharmaceutical ingredient; CLF, coarse lactose fines; Carrier; DPI, dry powder inhaler; Dry powder inhaler; ED, emission dose; ER, elongation ratio; FLF, fine lactose fines; FPF, fine particle fraction; FR, flatness ratio; Fshape, shape factor; Fsurface, surface factor; MFV, minimum fluidization velocity; Morphology; PDD, pulmonary drug delivery; Particle size; Performance; RO, roundness; Surface roughness; dae, aerodynamic diameter; pMDI, pressurized metered-dose inhaler.