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Assessment of 99mTc-succimer residual activity using inert nonreactive syringes
Wendy Galbraith1, Xinlian Chen2, Katie Talley3
1University of Oklahoma College of Pharmacy, Oklahoma City, Oklahoma wendy-galbraith@ouhsc.edu.
Unlabelled:
It has been widely reported that (99m)Tc-succimer adsorbs to plastic syringes significantly (up to 50%), often resulting in a lower administered dose than intended or inaccurate dosing. This adsorption rate is especially problematic in the pediatric population. To improve (99m)Tc-succimer dosing, we compared the adsorption of (99m)Tc-succimer with 2 types of syringes: silicone-coated syringes with nonlatex rubber on the plunger and inert nonreactive syringes with no silicone coating and no rubber on the plunger.
Methods:
(99m)Tc-succimer kits were compounded according to the manufacturer's instructions. (99m)Tc-succimer doses (37-185 MBq) were drawn into 3-mL (silicone-coated or inert nonreactive) syringes in a 1-mL volume. Thirty min, 1 h, 2 h, and 4 h later, the syringes were assayed in a dose calibrator and assayed again after being emptied and rinsed with saline. In addition, we examined the data collected from 129 (99m)Tc-succimer doses administered in a pediatric department, in which 52 were dispensed in silicone-coated syringes and 77 were dispensed in inert nonreactive syringes. The doses were assayed immediately before and after injection. The syringes were flushed with normal saline.
Results:
The labeling efficiency of the (99m)Tc-succimer kits was more than 95%. Residual activity left in the inert nonreactive syringes was 0.73% (SD, ±0.18%), which was significantly lower than the activity left in the silicone-coated syringes, 20.9% (SD, ±5.6%; P < 0.0001). The extent of adsorption did not change significantly between 30 min and 4 h of incubation. The clinical data showed that the residual activity was 30.6% (SD, ±12.5%) from doses dispensed in silicone-coated syringes and 6.38% (SD, ±2.95%) from doses dispensed in inert nonreactive syringes (P < 0.001).
Conclusion:
The inert nonreactive syringes had significantly less residual of (99m)Tc-succimer than silicone-based syringes, making it possible to accurately administer calculated doses of (99m)Tc-succimer to pediatric patients.
