title: Stability of stabilized 99mTc-D,L-HMPAO stored in vials and syringes.
abstract: Our objective was to determine the stability of stabilized (99m)Tc-hexamethylpropylene amine oxime ((99m)Tc-d,l-HMPAO) dispensed by vial and syringe, with the storage time and labeling activity varied.
  
  
  METHODS
  (99m)Tc-d,l-HMPAO was labeled according to the manufacturer's instructions, but with modification of the (99m)TcO(4)Na activity. Two groups were prepared: 1,110 MBq (30 mCi) and 2,600-3,700 MBq (70.3-100 mCi). Five minutes after labeling, the radiochemical purity (RCP) of the vial content was determined. Afterward, the same activity was distributed into two 2-mL syringes and into the manufacturer's vial. In one of the syringes, the radiopharmaceutical stayed in contact with the needle for 4 h. At 2 and 4 h after labeling, the RCP of the vial and syringe content was checked and compared.
  
  
  RESULTS
  The mean RCP of stabilized (99m)Tc-d,l-HMPAO labeled with 1,110 MBq (30 mCi) and stored in a vial decreased from 93.1% at 5 min to 92.1% at 2 h and to 91.1% at 4 h. With storage in a syringe, the RCP decreased from 89.8% at 2 h to 88.7% at 4 h. This diminution increased for labeling with higher activities (2,600-3,700 MBq [70.3-100 mCi]), ranging from 91.4% at 5 min, 89.0% at 2 h, and 85.3% at 4 h in a vial and from 85.9% at 2 h to 80.2% in a syringe. (99m)TcO(2) and secondary (99m)Tc-HMPAO were the main impurities at t = 0. (99m)TcO(4)(-) was an impurity that increased with time in both vials and syringes but significantly so in syringes. All these impurities were higher with labeling activities in the range of 2,600-3,700 MBq (70.3-100 mCi). Contact of the needle with (99m)Tc-d,l-HMPAO sharply decreased the RCP to 57.1% at 4 h.
  
  
  CONCLUSIONS
  The RCP of stabilized (99m)Tc-d,l-HMPAO decreases significantly in both vials and syringes with high labeling activities. The product is less stable when stored in a syringe than in a vial. The fraction of dose in contact with the needle affects the RCP results.
authors.affiliation: Servicio de Medicine Nuclear, Hospital Universitario Dr. Peset, Valencia, Spain. plancha_mca@gva.es
authors.forename: Maria
authors.initials: M
authors.lastname: Del Carmen Plancha-Mansanet
authors.forename: Elisa
authors.initials: E
authors.lastname: Caballero-Calabuig
authors.forename: Jesús
authors.initials: J
authors.lastname: Félix-Fontestad
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Reyes-Ojeda
authors.forename: Pablo
authors.initials: P
authors.lastname: Sopena-Novales
authors.forename: Pedro
authors.initials: P
authors.lastname: Abreu-Sánchez
authors.forename: Maria
authors.initials: M
authors.lastname: Del Carmen Cano-Terol
authors.forename: Ramón
authors.initials: R
authors.lastname: Sopena-Monforte
mesh_terms: D004353:Drug Evaluation, Preclinical; D004355:Drug Stability; D004356:Drug Storage / Q000379:methods*; D006207:Half-Life; D019275:Radiopharmaceuticals / Q000032:analysis / Q000737:chemistry; D013594:Syringes; D019690:Technetium Tc 99m Exametazime / Q000032:analysis* / Q000737:chemistry*
chemical_list: D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime