In Vivo Lung Deposition of Hollow Porous Particles from a Pressurized Metered Dose Inhaler

Purpose: PulmoSphere particles are specifically engineered for delivery by the pulmonary route with a hollow and porous morphology, physical diameters < 5 m, and low tap densities (circa 0.1 g.cm^-3). Deposition of PulmoSphere particles in the human respiratory tract delivered by pressurized metered dose inhaler (pMDI) was compared with deposition of a conventional micronized drug pMDI formulation. Methods: Nine healthy nonsmoking subjects (5 male, 4 female) completed a two-way crossover gamma scintigraphic study, assessing the lung and oropharyngeal depositions of albuterol sulfate, formulated as ^99mTc-radiolabeled PulmoSphere particles or micronized particles (Ventolin Evohaler^TM, GlaxoSmithKline, Ltd.) suspended in HFA-134a propellant. Results: Mean (standard deviation) lung deposition, (% ex-valve dose) was doubled for the PulmoSphere formulation compared with Evohaler pMDI (28.5 (11.3) % vs. 14.5 (8.1) %, P < 0.01), whereas oropharyngeal deposition was reduced (42.6 (9.0) % vs. 72.0 (8.0) %, P < 0.01). Both PulmoSphere and Evohaler pMDIs gave uniform deposition patterns within the lungs. Conclusions: These data provided proof of concept in vivo for the PulmoSphere technology as a method of improving targeting of drugs to the lower respiratory tract from pMDIs, and suggested that the PulmoSphere technology may also be suitable for the delivery of systemically acting molecules absorbed via the lung.