Stability of stabilized 99mTc-D,L-HMPAO stored in vials and syringes.
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.
Del Carmen Plancha-Mansanet
Maria
M
Servicio de Medicine Nuclear, Hospital Universitario Dr. Peset, Valencia, Spain. plancha_mca@gva.es
Caballero-Calabuig
Elisa
E
Félix-Fontestad
Jesús
J
Reyes-Ojeda
María Dolores
MD
Sopena-Novales
Pablo
P
Abreu-Sánchez
Pedro
P
Del Carmen Cano-Terol
Maria
M
Sopena-Monforte
Ramón
R
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*
D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime