title: The effect on radiochemical purity of modifications to the method of preparation and dilution of 99mTc-sestamibi.
abstract: BACKGROUND
  99mTc-sestamibi is a useful radiopharmaceutical for myocardial perfusion imaging, parathyroid imaging and breast tumour imaging. However, the preparation is time consuming and the limit of 3 ml on the volume of liquid that can be added to the Cardiolite kit vial means that it is often difficult to draw up small doses for patient studies.
  
  
  OBJECTIVE
  To modify the method of preparation of 99mTc-sestamibi in order to reduce the preparation time and to give a preparation which is more convenient for withdrawing patient doses.
  
  
  METHODS
  A modified kit was prepared by reconstituting a Cardiolite kit vial with 3 ml Sodium Chloride Injection (0.9%) BP, sub-dividing it into two separate nitrogen-filled vials before adding sodium pertechnetate and boiling for radiolabelling. 99mTc-sestamibi was also prepared according to the manufacturer's recommended method and diluted with sodium chloride injection after preparation. Radiochemical purity was assessed by thin-layer chromatography and high-performance liquid chromatography.
  
  
  RESULTS
  99mTc-sestamibi prepared according to the manufacturer's recommended method had high radiochemical purity (96.9%+/-1.1%) and retained >90% radiochemical purity over 8 h following dilution. However, 99mTc-sestamibi prepared by the modified method gave variable and inconsistent results.
  
  
  CONCLUSIONS
  The modified method of preparation was not robust enough to give reproducibly high radiochemical purity. However, dilution of 99mTc-sestamibi prepared according to the manufacturer's recommended method was satisfactory. This study highlights problems with the analysis of 99mTc-sestamibi and the limitations of modifying the method of preparation.
authors.affiliation: Department of Pharmacy, St. Bartholomew's Hospital, London, UK. m.cooper@qmul.ac.uk
authors.forename: Maggie
authors.initials: M
authors.lastname: Cooper
authors.forename: Kate
authors.initials: K
authors.lastname: Dustan
authors.forename: Laure
authors.initials: L
authors.lastname: Rotureau
mesh_terms: D004341:Drug Evaluation; D005602:France; D007553:Isotope Labeling / Q000379:methods* / Q000592:standards*; D019275:Radiopharmaceuticals / Q000032:analysis / Q000138:chemical synthesis* / Q000592:standards*; D012016:Reference Values; D017256:Technetium Tc 99m Sestamibi / Q000032:analysis / Q000737:chemistry* / Q000592:standards*
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi