title: Stability of radioactive colloids for radiation synovectomy: influence of X-ray contrast agents, anaesthetics and glucocorticoids in vitro.
abstract: OBJECTIVE
  This in-vitro study investigated the influence of the contrast agents iothalamate (Conray) and special preparations of iotrolan (Isovist) and iopromide (Ultravist) without ethylenediaminetetraacetic acid (EDTA), the anaesthetic Scandicain and the glucocorticoid triamcinolone on the stability of 90Y-, 169Er- and 186Re-radiocolloids used for radiation synovectomy.
  
  
  METHODS
  Vials of 1 ml of synovial fluid and 0.02 ml of radiocolloid suspension (0.56-3.6 MBq) were mixed with 0.06, 0.6 and 1.0 ml of each contrast agent. In an additional series, 0.1 ml of Scandicain and 0.1 ml of triamcinolone were tested. Thin layer chromatography and ultrafiltration/centrifugation were performed between 1 h and 15 days after incubation with negative and positive controls.
  
  
  RESULTS
  Within 24 h, 0.6 and 1.0 ml of Conray had mobilized 5-20% of the 90Y and 169Er out of the colloids. No interference between 186Re-colloids and Conray was visible before the ninth day after incubation. Iotrolan and iopromide without EDTA had no effect on the stability at shorter incubation periods of up to 6 days. The addition of Scandicain did not produce low-molecular 90Y or 169Er in the presence of synovial fluid. The fraction of low-molecular 186Re reached 4% after 24 h. Triamcinolone did not have any effect on stability in the presence of synovial fluid.
  
  
  CONCLUSIONS
  The disintegration of the radioactive colloids can be attributed to either the formation of EDTA complexes or radiolytic effects. The volume of the injected contrast agent should be as small as possible to confirm correct intra-articular distribution.
authors.affiliation: Department of Nuclear Medicine, University of Cologne, Cologne, Germany. klaus.schomaecker@uni-koeln.de
authors.forename: Klaus
authors.initials: K
authors.lastname: Schomäcker
authors.forename: Markus
authors.initials: M
authors.lastname: Dietlein
authors.forename: Gynter
authors.initials: G
authors.lastname: Mödder
authors.forename: Barbara
authors.initials: B
authors.lastname: Boddenberg-Pätzold
authors.forename: Beate
authors.initials: B
authors.lastname: Zimmermanns
authors.forename: Thomas
authors.initials: T
authors.lastname: Fischer
authors.forename: Harald
authors.initials: H
authors.lastname: Schicha
mesh_terms: D000777:Anesthetics / Q000737:chemistry*; D003102:Colloids / Q000032:analysis* / Q000737:chemistry*; D003287:Contrast Media / Q000737:chemistry*; D004338:Drug Combinations; D004355:Drug Stability; D005938:Glucocorticoids / Q000737:chemistry*; D006207:Half-Life; D006801:Humans; D007592:Joint Diseases / Q000532:radiotherapy; D011868:Radioisotopes / Q000032:analysis* / Q000737:chemistry* / Q000627:therapeutic use; D011874:Radiometry; D019275:Radiopharmaceuticals / Q000032:analysis / Q000737:chemistry / Q000627:therapeutic use
chemical_list: D000777:Anesthetics; D003102:Colloids; D003287:Contrast Media; D004338:Drug Combinations; D005938:Glucocorticoids; D011868:Radioisotopes; D019275:Radiopharmaceuticals