title: Imaging the postdeposition dispersion of an inhaled surfactant aerosol.
abstract: BACKGROUND
  Aerodynamic forces provide the primary means of distributing aerosol medications within the lungs. Partial airway obstructions can limit both air flow and aerosol penetration into diseased zones. We hypothesize that low surface tension additives may help to disperse aerosol medications after deposition in the airways, improving dose uniformity and drug delivery to underventilated regions. To test this, we performed a pilot scintigraphy study of surfactant and saline deposition and postdeposition dispersion.
  
  
  METHODS
  Because inhaled antibiotics for cystic fibrosis provide an example of where self-dispersing medications may be useful, we administered calfactant and saline aerosols with added Technetium 99m sulfur colloid (Tc-SC; 100 nm filtered) on different days in randomized order to eight cystic fibrosis (CF) subjects (average FEV(1)%, p=85 ± 12%). Nebulized delivery was matched (similar aerosol sizes and volume delivery rates, fixed breathing patterns). Tc-SC distribution in the lungs was imaged continuously for 30 min after delivery.
  
  
  RESULTS
  Both aerosols were well tolerated. Aerosol distribution was mostly peripheral (58/42%) and initially similar for saline and surfactant. Changes in whole lung counts after 30 min were also similar. Peripheral lung activity decreased more rapidly on average with calfactant though the difference versus saline was not statistically significant. Central to peripheral count ratio decreased with saline and increased with calfactant and c/p changes approached significance (-0.05 ± 0.16 vs. 0.10 ± 0.10; p=0.07 Wilcoxon).
  
  
  CONCLUSIONS
  Our results lack statistical significance, but suggest that inhaled calfactant increased peripheral clearance, due to either surfactant-based dispersion or mucociliary effects. Further studies are needed to define the potential for low surface tension carriers to improve drug delivery.
authors.affiliation: Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. corcorante@upmc.edu
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Corcoran
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Thomas
authors.forename: Stephen
authors.initials: S
authors.lastname: Garoff
authors.forename: Robert D
authors.initials: RD
authors.lastname: Tilton
authors.forename: Todd M
authors.initials: TM
authors.lastname: Przybycien
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Pilewski
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000336:Aerosols; D000402:Airway Obstruction / Q000473:pathology; D001688:Biological Products / Q000008:administration & dosage*; D003550:Cystic Fibrosis / Q000188:drug therapy*; D016503:Drug Delivery Systems; D005260:Female; D006801:Humans; D008168:Lung / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D010865:Pilot Projects; D011663:Pulmonary Surfactants / Q000008:administration & dosage*; D011877:Radionuclide Imaging; D013671:Technetium Tc 99m Sulfur Colloid / Q000737:chemistry; D013997:Time Factors; D055815:Young Adult
chemical_list: D000336:Aerosols; D001688:Biological Products; D011663:Pulmonary Surfactants; D013671:Technetium Tc 99m Sulfur Colloid; C117342:calfactant