99Tcm-MAG3: in vitro stability and in vivo behaviour at different times after preparation.
A kit for preparing technetium-99m mercaptoacetyltriglycine (99Tcm-MAG3), a new radiopharmaceutical for gamma camera renography, is available commercially. A drawback to the use of this kit is the recommended 1h expiry for 99Tcm-MAG3. This short expiry is a consequence of the possible growth of an impurity which undergoes hepatobiliary excretion and might interfere with renal imaging. Radiochemical purity of 99Tcm-MAG3 was measured by high performance liquid chromatography at 0, 1 and 6 h after preparation and was found to be consistently greater than 95. 99Tcm-MAG3 was shown to contain five impurities, one of which increased from 0.5% to 1% over 6 h. Dilution of 99Tcm-MAG3 eliminated this effect. A two-part clinical study was undertaken. For Part I, 99Tcm-MAG3 was prepared at 400 MBq/4 ml. For Part II, 99Tcm-MAG3 was prepared at 1 GBq/4 ml then subdivided and diluted to give single doses of 175 MBq/2.5 ml. In both parts, 10 patients were injected within 1 h after preparation and 10 were injected 5-6 h after preparation. From gamma camera images of the abdomen acquired 30 min after injection, the % injected 99Tcm in gall bladder and liver were calculated. In both parts, the % injected 99Tcm in gall-bladders and livers of the 1 h group were compared with those in the 5-6 h group and not found significantly different (p greater than 0.05). In conclusion, 99Tcm-MAG3 prepared according to the methods described, can be used up to 6 h after preparation.
Millar
A M
AM
Department of Radiopharmacy, Royal Infirmary, Edinburgh, UK.
Wilkinson
A G
AG
McAteer
E
E
Best
J J
JJ
D004355:Drug Stability; D005704:Gallbladder / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000378:metabolism; D009842:Oligopeptides / Q000493:pharmacokinetics; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D011877:Radionuclide Imaging; D011933:Reagent Kits, Diagnostic; D017263:Technetium Tc 99m Mertiatide; D013997:Time Factors
D009842:Oligopeptides; D015609:Organotechnetium Compounds; D011933:Reagent Kits, Diagnostic; D017263:Technetium Tc 99m Mertiatide