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  • 1 Biomira Inc. Precess Formulation and Technology 2011, 94 Street T6N 1H1 Edmonton Alberta (Canada)
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The chemical condition of99mTc eluate obtained from a99Mo-99mTc generator is a function of the source, time elapsed after elution and age of the eluate. The radiochemical purity and stability of99mTc labeled MAb-170 (Tru-Scint®ADTM, photoactivated monoclonal antibody kit) preparations was evaluated comparing pertechnetate source of known age and elution history. The effect of H2O2, a radiolytic impurity in99mTc eluates, on the active kit components stannous ion and photoactivated MAb and radiolabeling, yield has been investigated. The lyophilized Tru-Scint® ADTM kit has been labeled with 20 to 80 mCi in 0.5 to 4.0 ml of Sodium Pertechnetate99mTc Injection, USP. The eluates were obtained from three brands of generators and used up to six hours after elution. The kits were reconstituted either with Sodium Pertechnetate99mTc Injection, USP or Sodium Chloride Injection, USP, 0.9% containing known amounts of H2O2. The reconstituted kits were analyzed for radiolabeling yield and radiochemical impurities, stannous ion and protein sulfhydryl group. The results indicated that the radiolabeling yield is a function of both the chemical condition of99mTc eluate, generator brand and the radiolabeling parameters like reconstitution volume and activity. The observed radiolabeling yield differences did not depend on the amount of chemical technetium in the eluate. The major radiochemical impurities at 15-minute post labeling have been identified as the99mTc-buffer complex and column adsorbed reduced99mTc (99mTc-Ad) species and not the unreduced99mTcO 4 .