Effect of inhaled surfactant on pulmonary deposition and clearance of technetium-99m-DTPA radioaerosol.
To establish the effect of an aerosolized synthetic surfactant (Exosurf) on pulmonary 99mTc-diethylenetriamine pentaacetic acid (DTPA) aerosol deposition and clearance, radioaerosol studies were performed at varying times and under varying conditions after surfactant inhalation in canine lungs.


METHODS
Twenty-three dogs had a baseline 99mTc-DTPA study; 2 days later the study was repeated after inhalation of a 1.5-ml/kg dose of Exosurf aerosolized by an ultrasonic nebulizer. The clearance half-time (T1/2) of 99mTc-DTPA from each lung was measured at different times (from 10 min to 3 hr) after Exosurf inhalation. For comparison, five animals had a 99mTc-DTPA study 10 min after inhalation of the same dose of saline as Exosurf. An additional five animals inhaled a 99mTc-DTPA-Exosurf mixture to investigate the distribution of Exosurf.


RESULTS
Technetium-99m-DTPA distributed uniformly without significant changes in penetration indexes before and after inhalation of Exosurf and the 99mTc-DTPA-Exosurf mixture. After Exosurf inhalation, 99mTc-DTPA clearance at 10 min (T1/2; 35.6 +/- 8.7 min; n = 6) and 40 min (29.4 +/- 6.3 min; n = 4) was significantly prolonged compared with the matched baseline values (24.7 +/- 6.4 min, p < 0.0001; and 21.7 +/- 8.9 min, p = 0.01, respectively). However, later clearance times were not prolonged. By contrast, after saline inhalation, 99mTc-DTPA distributed inhomogeneously, and clearance times T1/2) were not altered from the matched baseline values.


CONCLUSIONS
Aerosolized Exosurf distributes homogeneously in the lungs. Exosurf initially retards 99mTc-DTPA aerosol clearance, but 99mTc-DTPA transalveolar clearance returns to baseline rates within 1-2 hr. Technetium-99m-DTPA aerosol clearance measurements can be used to monitor the effect of inhaled Exosurf on pulmonary epithelial integrity.
Suga
K
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Department of Radiology, Columbia-Presbyterian Medical Center, New York, New York 10032, USA.
Mitra
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A
Domingues
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Alderson
P O
PO
D000280:Administration, Inhalation; D000336:Aerosols; D000818:Animals; D004285:Dogs; D004338:Drug Combinations; D005233:Fatty Alcohols / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D008168:Lung / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000378:metabolism; D010767:Phosphorylcholine; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D011663:Pulmonary Surfactants / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate; D013997:Time Factors
D000336:Aerosols; D004338:Drug Combinations; D005233:Fatty Alcohols; D011663:Pulmonary Surfactants; D019275:Radiopharmaceuticals; D010767:Phosphorylcholine; D011092:Polyethylene Glycols; C047049:dipalmitoylphosphatidylcholine, hexadecanol, tyloxapol drug combination; D016284:Technetium Tc 99m Pentetate