title: The retention and distribution in the rabbit knee of a radionuclide complexed with a lipophilic chelator in liposomes.
abstract: The application of radiosynovectomy to patients with rheumatoid arthritis has been severely restricted by the difficulty of preventing leakage of the radioisotope from the joint cavity. We have synthesised a lipophilic chelator, 3-cholesteryl 6-[N'-iminobis(ethylenenitrilo)-tetraacetic acid]hexyl ether (Chol-DTTA) which can complex with a variety of beta-emitting radionuclides and is incorporated into the lipid phase of liposomes. The retention in the synovial cavities of rabbit knees of liposomes containing Chol-DTTA, complexed with the gamma-emitting tracer 51Cr, has been measured over a period of 21 days and compared with colloidal and water-soluble preparations. The distribution of the radionuclide between the tissues of the joint was also examined. Results show retention of 51Cr delivered in chelator liposomes to be greater than 99% after 24 h. At this time, over 93% of the radioactivity had become associated with the synovium. We conclude that chelator liposomes offer considerable promise as vehicles for radioisotopes in radiosynovectomy.
mesh_terms: D000818:Animals; D002614:Chelating Agents / Q000378:metabolism*; D002784:Cholesterol / Q000031:analogs & derivatives* / Q000378:metabolism; D002860:Chromium Radioisotopes / Q000378:metabolism*; D007717:Knee / Q000000981:diagnostic imaging* / Q000378:metabolism; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000378:metabolism; D008081:Liposomes / Q000008:administration & dosage; D011817:Rabbits; D011877:Radionuclide Imaging; D013583:Synovial Membrane / Q000000981:diagnostic imaging / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D002614:Chelating Agents; D002860:Chromium Radioisotopes; D008081:Liposomes; C045163:3-cholesteryl 6-(N-iminobis(ethylenenitrilo)tetracetic acid)hexyl ether; D002784:Cholesterol