title: In vitro and in vivo aspects of quantifying intrapulmonary deposition of a dry powder radioaerosol.
abstract: Pulmonary delivery of pharmaceutical aerosols can be quantified using gamma scintigraphy. Technetium-99m, the most commonly used radionuclide in scintigraphic studies, cannot be incorporated into the drug molecule and, therefore, may be distributed differently from the drug itself, particularly if the drug is presented as a solid in a liquid suspension or as a dry powder formulation. This study demonstrated the importance of using conditions relevant to the in vivo situation in the in vitro characterisation of a dry powder aerosol of 99mTc-labelled lactose. The influence of inspiratory flow on the distribution of aerosol within the lungs was investigated in eight healthy subjects who inhaled the 99mTc-labelled lactose at four flows (30,40,60 and 80 l/min). No differences in penetration index (PI) or count density distribution of radioactivity were seen, indicating that regional distribution of aerosol in healthy airways was insensitive to differences in the inspiratory effort exerted by the subject while inhaling the experimental dry powder radioaerosol.
authors.affiliation: Department of Clinical Physiology, Lund University, Malmö University Hospital, S-205 02, Malmö, Sweden. eva.bondesson@astrazeneca.com
authors.forename: Eva
authors.initials: E
authors.lastname: Bondesson
authors.forename: Lars
authors.initials: L
authors.lastname: Asking
authors.forename: Lars
authors.initials: L
authors.lastname: Borgström
authors.forename: Lars-Erik
authors.initials: LE
authors.lastname: Nilsson
authors.forename: Eva
authors.initials: E
authors.lastname: Trofast
authors.forename: Per
authors.initials: P
authors.lastname: Wollmer
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000704:Analysis of Variance; D018592:Cross-Over Studies; D006801:Humans; D007785:Lactose / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D011208:Powders; D011877:Radionuclide Imaging; D013667:Technetium; D014018:Tissue Distribution
chemical_list: D011208:Powders; D013667:Technetium; D007785:Lactose