In vitro adsorption of Tc-99(m)-MIBI, Tc-99(m)-tetrofosmin, Tc-99(m)-furifosmin and (TcO4-)-Tc-99-O-m onto tubes

Adsorption of radiopharmaceuticals onto disposable syringes has been report ed to amount to levels of almost 50%. Data on adsorption of radiopharmaceut icals onto materials used for in vitro studies are extremely limited. We as sessed the extent of adsorption of Tc-99(m) hexakis(2-methoxyisobutylisonit rile) (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 incuba tion media, temperature and time of incubation was evaluated. Total (not co rrected for adsorption) uptake was compared with corrected, net cellular up take in SK-BR-3, MCF-7 and liposarcoma cell lines. Values of adsorption ran ging 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 de pendent on the incubation time as well on the incubation temperature and so me of the incubation media investigated. Our findings indicate that systema tic in investigations to evaluate the adsorption of radiopharmaceuticals on to materials used during in vitro studies of cellular uptake should be cons idered a mandatory aspect of quality control. ((C) 2001 Lippincott Williams & Wilkins).