[The effect of contaminants on characteristics of 99mTC radiopharmaceuticals]

The influence of 99Tc, oxygen and cupric ions on labeling yield of eight radiopharmaceuticals was examined. The results obtained for commercial and experimental preparations were compared. The latter were formulated so that the content of 99Tc was 4 times, hydrogen peroxide 5 times and copper 50 times higher than in commercial preparations. It was found that these impurities did not affect labeling of 99mTc(Sn)tetracyclin, 99mTc(Sn)dimercaptosuccinate and 99mTc(Sn)diethylida. Long-living 99Tc did not affect any preparations. Oxygen influenced in lesser extent 99mTc(Sn) DTPA, 99mTc(Sn)pyrophosphate and 99Tc(Sn) dicarboxy-propane diphosphonate but strongly 99mTc(Sn) phytate 99mTc(Sn)methylene diphosphonate. Copper influenced only 99mTc(Sn)-methylene diphosphonate. Therefore this preparation was examined in broader range of copper concentrations. According to the results of radiochemical and biodistribution analyses it was concluded that under the experimental conditions the effect of oxygen and copper resulted in an increased content of free 99mTc-pertechnetate in the examined preparations.