EFFECT OF CHEMICAL CONDITION OF TC-99M SODIUM PERTECHNETATE ON THE ACTIVE KIT COMPONENTS AND RADIOLABELING YIELD OF TRU-SCINT(R) AD(TM) MONOCLONAL-ANTIBODY KIT

The chemical condition of Tc-99m eluate obtained from a Mo-99-Tc-99m g enerator is a function of the source, time elapsed after elution and a ge of the eluate. The radiochemical purity and stability of Tc-99m lab eled MAb-170 (Tru-Scint(R)ADTM, photoactivated monoclonal antibody kit ) preparations was evaluated comparing pertechnetate source of known a ge and elution history. The effect of H2O2, a radiolytic impurity in T c-99m eluates, on the active kit components stannous ion and photoacti vated MAb and radiolabeling yield has been investigated. The lyophiliz ed Tru-Scint(R) AD(TM) kit has been labeled with 20 to 80 mCi in 0.5 t o 4.0 mi of Sodium Pertechnetate Tc-99m Injection, USP. The eluates we re obtained from three brands of generators and used up to six hours a fter elution. The kits were reconstituted either with Sodium Pertechne tate Tc-99m Injection, USP or Sodium Chloride Injection, USP, 0.9% con taining known amounts of H2O2 The reconstituted kits were analyzed for radiolabeling yield and radiochemical impurities, stannous ion and pr otein sulfhydryl group. The results indicated that the radiolabeling y ield is a function of both the chemical condition of Tc-99m eluate, ge nerator brand and the radiolabeling parameters like reconstitution vol ume 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 identifi ed as the Tc-99m-buffer complex and column adsorbed reduced Tc-99m (Tc -99m-Ad) species and not the unreduced (TcO4-)-Tc-99m.