Rd. Gunasekera et al., Adsorption of radiopharmaceuticals to syringes leads to lower administeredactivity than intended, NUCL MED C, 22(5), 2001, pp. 493-497
In this study we examined the delivered activity of radiopharmaceuticals in
jected into patients and the various factors which lead to incomplete deliv
ery. Four commonly used Tc-99(m) radiopharmaceuticals were included, namely
pertechnetate, methylene diphosphonate (MDP), macro-aggregated albumin (MA
A) and tetrofosmin. There was no appreciable residual activity after inject
ion of pertechnetate and MDP other than that due to the dead space in syrin
ges (0.06 ml, 4% of measured activity). However, there was considerable res
idual activity following an MAA injection. This was particularly dependent
on the radiopharmaceutical residence time in the syringe prior to injection
. If MAA was pre-dispensed there was up to 80% of activity remaining in the
syringe following injection. We have shown that this activity is not bound
and can be decreased by agitating the syringe prior to the injection. For
tetrofosmin, the activity remaining in the syringe was shown to be mostly d
ue to adsorption of the tetrofosmin onto the plastic syringe (up to 30% of
the activity); in particular, onto the rubber plunger. The amount of bindin
g probably depends on the formulation of the rubber plunger and the plastic
barrel, which varies between manufacturers. Of the three commonly used syr
inge brands (Becton-Dickinson, Sherwood, and Braun syringes) the Braun syri
nges were shown to have the least binding (6%) and would be most suitable f
or tetrofosmin injection. We recommend the use of Braun syringes for tetrof
osmin. We also recommend that pre-dispensed MAA injections should be gently
agitated before injection into the patient. No special precautions are nec
essary for pertechnetate or MDP injections. ((C) 2001 Lippincott Williams &
Wilkins).