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The influence of drugs on the labeling of red blood cells and plasma proteins with 99mTc has been reported. Any drug, which alters the labeling of the tracer, could be expected to modify the disposition of the radiopharmaceuticals. Red blood cells (RBC) labeled with technetium-99m (99mTc) are used for several evaluations in nuclear medicine. We have evaluated the effect of Thuya occidentalis, Peumus boldus and Nicotiana tabacum (tobacco) extracts on the labeling of RBC and plasma and cellular proteins with 99mTc. Blood was incubated with the drugs. Stannous chloride (SnCl2) solutions and 99mTc were added. Plasma (P) and blood cells (BC) were separated. The percentage of radioactivity (%ATI) bound to P and BC was determined. The %ATI on the plasma and cellular proteins was also evaluated by precipitation of P and BC samples with trichloroacetic acid (TCA) and isolation of soluble (SF) and insoluble (IF) fractions. The analysis of the results shows that there is a decrease in %ATI (from 97.64 to 75.89 percent) in BC with Thuya occidentalis extract. The labeling of RBC and plasma proteins can be decreased in presence of tobacco. This can be due either a direct or indirect effect (reactive oxygen species) of tobacco. The analysis of radioactivity in samples of P and BC isolated from samples of whole blood treated with Peumus boldus showed a rapid uptake of the radioactivity by blood cells in the presence of the Peumus boldus, whereas there was a slight decrease in the amount of 99mTc radioactivity in the TCA-insoluble fraction of plasma. This study shows that extracts of some medicinal plants can affect the radiolabeling of red blood cells with 99mTc using an in vitro technique.

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Ilex paraguariensis (mate-tea) has been used to treat type-2 diabetes and emphysema. This tea presents antioxidant activity and promotes satiety, body weight lowering and improves bone mineral density. Blood constituents have been labeled with technetium-99m ( 99m Tc) and this labeling depends on the presence of a reducing agent. Stannous chloride has been widely utilized with this purpose. The influence of natural and synthetic drugs in this procedure has been reported. It was evaluated with effect of an aqueous mate-tea extract on the labeling of blood constituents with 99m Tc and on the morphology of erythrocyte. Blood samples of Wistar rats were incubated with mate-tea extract, stannous chloride and 99m Tc-sodium pertechnetate. Blood cells (BC) and plasma (P) were isolated. BC and P were also precipitated and soluble (SF) and insoluble (IF) fractions separated. The radioactivity was counted and percentage of incorporated radioactivity (%ATI) determined. Blood smears were performed for morphological evaluation. The data show a significant (p < 0.05) alteration of %ATI in BC, IF-C and IF-P as well as on the erythrocyte morphology. These findings could be related to the redox properties of the substances of the mate-tea extract, as well as due to the interference in the transport of stannous and/pertechnetate into the BC due to the morphological alterations of the erythrocytes.