In vitro adsorption of 99Tcm-MIBI, 99Tcm-tetrofosmin, 99Tcm-furifosmin and 99TcmO4- onto tubes

Adsorption of radiopharmaceuticals onto disposable syringes has been reported to amount to levels of almost 50%. Data on adsorption of radiopharmaceuticals onto materials used for in vitro studies are extremely limited. We assessed the extent of adsorption of Tc-99(m) hexakis(2-methoxyisobutylisonitrile) (Tc-99(m)-MIBI), Tc-99(m)-tetrofosmin, Tc-99(m)-furifosmin and (TcO4-)-Tc-99-O-m onto tubes used for in vitro measurement of cellular uptake of these radiopharmaceuticals. The influence on adsorption of different incubation media, temperature and time of incubation was evaluated. Total (not corrected for adsorption) uptake was compared with corrected, net cellular uptake in SK-BR-3, MCF-7 and liposarcoma cell lines. Values of adsorption ranging from 0.94+/-0.13% to 7.07+/-0.46% were found. The extent of adsorption of all the radiopharmaceuticals varied with the type of incubation medium and the incubation temperature. With Tc-99(m)-furifosmin, adsorption was dependent on the incubation time as well on the incubation temperature and some of the incubation media investigated. Our findings indicate that systematic in investigations to evaluate the adsorption of radiopharmaceuticals onto materials used during in vitro studies of cellular uptake should be considered a mandatory aspect of quality control. ((C) 2001 Lippincott Williams & Wilkins).