Our objective was to determine the stability of stabilized 99m Tchexamethylpropylene 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 5 0. 99m TcO 4 2 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. Conclusion: 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.
Background: Inadequate temperature affects the stability of intact parathyroid hormone (i-PTH) kits. Room temperature during transport modifies i-PTH results. Method: Percent bound (%B/Bmax) and concentrations ( pmol/L) of standards, controls (C1, C2) and pool from eight standard curves were divided into: group I (three curves from kits kept at room temperature for more than 48 h) and group II (five curves from kits kept at 2 -88C) during transport. i-PTH was measured using Scantibodies total i-PTH assay with RIAMAT-280. Results: %B/Bmax for standards, C1 and C2 were significantly higher in group I versus II (P ¼ 0.04). %B/Bmax for the pool were significantly lower in group I (P ¼ 0.001). i-PTH pool concentration in group I was 51% lower (95% confidence interval, 47-53%, P ¼ 0.001); differences were not significant for C1 (P ¼ 0.25) and C2 (P ¼ 0.57) in both groups. Conclusion: Room temperature on i-PTH kit during transport alters the standard curve, resulting in a decrease in i-PTH. Using a pool as internal quality control allows the detection of these changes not detected by kit controls.
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