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The many desirable characteristics of technetium-99m (99mTc) have stimulated the development of labeling techniques for different molecular and cellular structures. It is generally accepted that a variety of factors other than disease can alter the bioavailability of radiopharmaceuticals and one such factor is the drug therapy. The use of medicinal plants has increased in the last decades all over the world. Punica granatum (pomegranata) is used as food or as medication in folk medicine for antiviral, anthelmintic, antifungal, antibacterial and antimicrobial activity. We have studied in rats, the effect of the medicinal plant Punica granatum on the bioavailability of the radiopharmaceutical 99mTc-sodium pertechnetate (Na(99m)TcO4). The infusion of pomegranata was administered by intragastric via into Wistar rats during seven days. After that, the animals received by ocular plexus via, 0.1 ml of the Na(99m)TcO4 (3.7MBq) and the animals were rapidly sacrificed after 5, 20 and 40 min. The organs were isolated (brain, heart, thyroid, liver, lungs, kidneys, stomach, testis, intestines, pancreas, spleen, bladder, muscle and bone), the radioactivity determined in a well counter, the percentages of radioactivity (%ATI) in the organs were calculated and statistical analyses were performed by Wilcoxon test (p < 0.05). The results have shown a significant (p < 0.05) increase of the activity of the Na(99m)TcO4 in spleen, heart, stomach, liver, stout bowel, pancreas, lungs and testis at 5 min. Twenty minutes after the administration of the radiopharmaceutical, the analysis of the results reveals a significant (p < 0.05) increase of the %ATI in heart, stomach, femur, pancreas, lungs and kidneys. Forty minutes after the administration of the Na(99m)TcO4, the results show a significant (p < 0.05) increase in spleen, brain, heart, stomach, liver, stout bowel, muscle, femur, lungs, pancreas, kidneys and testis. These results can be justified by therapeutic effect of this extract and/or by generation of active metabolites capable to interfere with the biodistribution of the studied radiopharmaceutical.

Natural products are widely used as food or food additives or medicines for humans. We are trying to develop a model to assess the possible toxic properties of natural products, such as Fucus vesiculosus, utilized in popular medicine. Red blood cells (RBC) labeled with technetium-99m (99mTc) are used in various procedures in nuclear medicine. This labeling procedure depends on a reducing agent, and stannous chloride is used. There is evidence that this labeling may be altered by drugs. We have investigated the possibility that F. vesiculosus extract is capable of altering the labeling of blood elements with 99mTc. Blood was incubated with F. vesiculosus extract and stannous chloride solution and Tc-99m added. Blood was centrifuged and plasma (P) and blood cells (BC) were isolated. Samples of P or BC were also precipitated, centrifuged and insoluble (IF) and soluble (SF) were separated. The percentages of radioativity (%ATI) in BC, IF-P and IF-BC were calculated. Histological preparations of the RBC treated with F. vesiculosus revealed that this extract is capable of promoting important modifications on the shape of the RBC. The%ATI decreased on BC from 93.6+/-2.3 to 29.0+/-2.7, on IF-P from 77.6+/-1.2 to 7.5+/-1.0 and on IF-BC from 80.0+/-3.4 to 12.6+/-4.8. Once the RBC labeling procedure with 99mTc depends on the presence of stannous (+2) ions, the substances present in the F. vesiculosus extract should increase the valence of these ions to stannic (+4). This would decrease the%ATI on blood elements and indicate the presence of oxidant agents in the F. vesiculosus extract.

There are evidences that some drugs used for the human diseases can modify the biodistribution of radiopharmaceuticals. The N-methyl meglumine antimoniate, commercially known as glucantime (Rhodia, Brazil), is the elected drug for the treatment of all the clinical forms of leishmaniasis. As therapeutic drugs can present important toxic effects, we studied the effects of the glucantime on the kinetic of biodistribution of radiopharmaceuticals. To study the glucantime effect on the biodistribution of technetium-99m-methylenediphosphonic acid (99mTc-MDP), glucantime IM (80 mg/kg/day) was administered into male Wistar rats (3 months old age) in single dose during 7 days. 99mTc-MDP was injected 1 hr after the last dose. The animals (n = 24) were divided into two groups: treated (n = 12) and control (n = 12) and they were rapidly sacrificed, respectively, in 3 periods (5, 30 and 120 min) after administration of the 99mTc-MDP. The organs were isolated (brain, heart, thyroid, lungs, kidneys, testis, stomach, intestines, pancreas, spleen, liver, muscle, bone and bladder) and the percentages of radioactivity (%ATI) in each organ were calculated. The results were analyzed by the Wilcoxon test (p < 0.05). The analysis of the results has shown a significant increase of the %ATI after 5 min administration of the 99mTc-MDP in spleen, kidneys, testis, heart, liver and a reduction of %ATI in bladder. Thirty minutes after administration of the 99mTc-MDP, the analysis ofthe results reveals a significant reduction of the %ATI in femur, kidneys, thin bowel, lungs, heart, liver and an increase in abdominal muscle and stout bowel. One hundred-twenty min after administration of the 99mTc-MDP, the analysis of the results shows a significant reduction of the %ATI in spleen, thyroid, blood, femur, kidneys, liver and an increase in bladder, pancreas and lungs. Biochemical dosages were also performed before (control group, n = 12) and after (treated group, n = 12) treatment with glucantime. There was a significant (p < 0.05) decrease to the biochemical levels after the treatment with glucantime in following dosages: blood urea nitrogen, creatinine, alkaline phosphatase, lactic dehydrogenase, aspartate amino transferase, total creatine kinase, total protein, globulin and albumin. These results were compared with the control group, without glucantime, and statistical analyses were performed (t-student test, p < 0.05). These results could be associated with the biological effects and/or metabolization of the studied drug.