title: Pulmonary absorption of aerosolized fluorescent markers in the isolated rabbit lung.
abstract: For the development of aerosolized controlled release formulations such as liposomes or nanoparticles, the use of suitable model drugs is necessary. This study compared the pulmonary absorption of the three structurally diverse fluorescent markers 5(6)-carboxyfluorescein (CF), 8-methoxypyrene-1,3,6-trisulfonic acid trisodium salt (MPTS) and rhodamine 6G (R6G) after nebulization in an isolated, perfused and ventilated rabbit lung. Aerosol particle size and lung deposition as well as lipophilicity of the fluorescent markers were determined. Dye concentrations were measured in the recirculating buffer and in the bronchoalveolar lavage. The MMAD of the dye aerosols ranged between 4.70 and 4.88 microm, total lung deposition was 0.40+/-0.05 ml. The 1-octanol/water partition coefficient as measure for lipophilicity was -3.45+/-0.16 for CF, -4.95+/-0.21 for MPTS and 2.69+/-0.18 for R6G. The perfusate concentration showed an increase to approximately 400 ng/ml (53.4+/-6.8% of the intrapulmonary deposited dye) for CF and approximately 230 ng/ml (29.1+/-2.0%) for MPTS, respectively; R6G concentration increased in the first 30 min to approximately 38 ng/ml followed by a gradual decrease to approximately 26 ng/ml (3.3+/-0.7%). In conclusion, these data suggest that the hydrophilic dye CF is suitable to study drug transport from aerosolized controlled release formulations across the lung barrier. In contrast, the highly water-soluble fluorescent probe MPTS demonstrates insufficient recovery and the lipophilic R6G high accumulation in lung tissue.
authors.affiliation: Medical Clinic II, Department of Internal Medicine, Justus-Liebig-University Giessen, Klinikstrasse 36, 35392 Giessen, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Lahnstein
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmehl
authors.forename: Ute
authors.initials: U
authors.lastname: Rüsch
authors.forename: Monika
authors.initials: M
authors.lastname: Rieger
authors.forename: Werner
authors.initials: W
authors.lastname: Seeger
authors.forename: Tobias
authors.initials: T
authors.lastname: Gessler
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D000818:Animals; D001692:Biological Transport; D001992:Bronchoalveolar Lavage Fluid; D003692:Delayed-Action Preparations; D005452:Fluoresceins / Q000493:pharmacokinetics*; D005456:Fluorescent Dyes / Q000493:pharmacokinetics*; D057927:Hydrophobic and Hydrophilic Interactions; D066298:In Vitro Techniques; D008168:Lung / Q000378:metabolism; D008297:Male; D011721:Pyrenes / Q000493:pharmacokinetics*; D011817:Rabbits; D012235:Rhodamines / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: C529640:8-methoxypyrene-1,3,6-trisulfonic acid trisodium salt; D000336:Aerosols; D003692:Delayed-Action Preparations; D005452:Fluoresceins; D005456:Fluorescent Dyes; D011721:Pyrenes; D012235:Rhodamines; C026188:rhodamine 6G; C024098:6-carboxyfluorescein