title: Respiratory clearance of aerosolized radioactive solutes of varying molecular weight.
abstract: To determine the influence of varying molecular weight (mol wt) on respiratory clearance of aerosolized solutes, we studied eight radiopharmaceuticals, each administered to four dogs: sodium 99mTc pertechnetate (TcO4), 99mTc glucoheptonate ([99mTc]GH), 51Cr-ethylenedinitrotetraacetate ([51Cr]EDTA), 99mTc diethylenetriaminepentaacetate ([99mTc] DTPA), 111In diethylenetriaminepentaacetate ([111In]DTPA), 67Ga desferoxaminemesylate ([67Ga]DFOM), 99mTc dextran ([99mTc]DX) and 111In transferrin ([111In]TF). After aerosolization (0.8 m MMD, 2.4 GSD), clearance was determined for 30 min and then corrected by intravenous injection for nonairspace radioactivity. In-TF clearance (0.11 +/- 0.10%/min) was lower than TcO4 (6.32 +/- 0.62%/min), [99mTc]GH (1.50 +/- 0.37%/min), [51Cr]EDTA (2.38 +/- 1.02%/min), [99mTc]DTPA (3.51 +/- 0.40%/min), [111In]DTPA (2.35 +/- 0.42%/min), [67Ga] DFOM (1.99 +/- 0.49%/min) and [99mTc]DX (1.81 +/- 0.75%/min) clearances (p less than 0.001). TcO4 clearance was higher than others (p less than 0.001). Technetium binding to DX was unsatisfactory; aerosolization caused unbinding from DTPA. We conclude that respiratory clearance of large mol wt solutes within 30 min is negligible and, that clearance of molecules between 347-5,099 daltons differs greatly, suggesting that binding and/or intrapulmonary retention affect transfer.
mesh_terms: D000818:Animals; D002860:Chromium Radioisotopes; D003676:Deferoxamine / Q000378:metabolism*; D003911:Dextrans / Q000378:metabolism*; D004285:Dogs; D004492:Edetic Acid / Q000378:metabolism*; D005710:Gallium Radioisotopes; D007204:Indium; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism*; D004369:Pentetic Acid / Q000378:metabolism*; D011877:Radionuclide Imaging; D013400:Sugar Acids / Q000378:metabolism*; D013667:Technetium; D014168:Transferrin / Q000378:metabolism*
chemical_list: D002860:Chromium Radioisotopes; D003911:Dextrans; D005710:Gallium Radioisotopes; D013400:Sugar Acids; D014168:Transferrin; D007204:Indium; D013667:Technetium; D004369:Pentetic Acid; D004492:Edetic Acid; C007852:alpha-glucoheptonic acid; D003676:Deferoxamine