Feasibility of fractionating MAG3 cold kit for cost reduction

99Tcm-MAG3 is the first 99Tcm-labelled radiopharmaceutical with a renal clearance similar to that of 131I-OIH. The cost of a unit dose of 99Tcm-MAG3 is comparatively less expensive than the cost of a combined 99Tcm-DTPA and 131I-OIH study dose. However, this cost-saving is dramatically reduced when only a few doses are withdrawn from a 99Tcm-MAG3 kit. Our goal in this study was to subdivide the MAG3 kit into fractions to reduce expense. By dissolving the lyophilized ingredients of MAG3 kits with either 5 or 10 ml N2-purged normal saline, the resultant liquid was divided into 1-ml aliquot vials filled with N2. The MAG3 aliquot vials were then frozen at -70 degrees C for future use. The radiochemical purity (RCP) of each vial was evaluated using the recommended Sep-Pak C18 column chromatography at different time periods. Over the entire 28-day evaluation period, the average RCP of the 5:1 dilution MAG3 vials after reconstitution with 3.7 GBq 99Tcm was maintained at 95.6 +/- 2.7% (n = 100) for 6 h, whereas the 10:1 fractionation MAG3 kits after labelling with 740 MBq 99Tcm showed an average RCP value of 98.4 +/- 2.1% (n = 100) for 6 h. Based upon these results, it is concluded that the fractionation of MAG3 kits and frozen storage in an N2 atmosphere not only maintains the stability of MAG3 but also provides a cost-effective method for using 99Tcm-MAG3.