Navegando por Palavras-chave "radiopharmaceuticals"

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    Complexation of Re-188-phosphonates: in vitro and in vivo studies
    (Oldenbourg Verlag, 2003-01-01) Faintuch, B. L.; Faintuch, Salomao [UNIFESP]; Muramoto, E.; IPEN; Universidade Federal de São Paulo (UNIFESP)
    MDP (methylenediphosphonate) and HEDP (hydroxyethylidene diphosphonate), both diphosphonates, and EDTMP (ethylenediamine tetramethylene phosphonic acid), a tetraphosphonate ligand, have been previously labeled with Re-188 for use in metastatic bone-pain palliation. the aim of this study was a comparison between the three complexes Re-188-MDP, Re-188-HEDP and Re-188-EDTMP concerning the complexation conditions, in order to achieve maximum yield, stability and bone uptake. Methods: MDP was dissolved in water and HEDP and EDTMP were dissolved in NaOH 1 N followed by reduction of pH with HCl 1 N. To all mixtures stannous chloride and (ReO4-)-Re-188 were added in a nitrogen atmosphere. the preparations were heated in boiling water bath for 15 min. Yield as well as radiochemical stability was estimated by ITLC. Different concentrations of phosphonates and stannous chloride were evaluated. Biodistribution studies in Swiss mice were done for the three Re-188-phosphonates that presented the best radiochemical yield. the optimal ligand concentration for maximum complexation was 85.2 mM for MDP, 72.8 mM for HEDP and 45.8 mM for EDTMP. the best amount of SnCl2-2H(2)O was 1.5 mg/mL for Re-188-HEDP and 1 mg/mL for both Re-188-MDP and Re-188-EDTMP. in these conditons the three complexes showed a complexation rate above 95%. Reasonable radiochemical stability for 24 hours was achieved by Re-188-EDTMP when employing ascorbic acid. All products showed a great uptake by the kidneys. Re-188-EDTMP had the greatest uptake by femur (3.1 +/- 0.2% ID/g) followed by Re-188-MDP (1.2 +/- 0.1% ID/g) and Re-188-HEDP (1.0 +/- 0.1% ID/g), 4 hours post injection. Re-188-EDTMP displayed a femur bone/muscle ratio of 28.5, Re-188-MDP 4.9 and Re-188-HEDP 4.9. in conclusion Re-188-EDTMP demonstrated the best potential as a radiopharmaceutical for bone cancer pain relief, encouraging further dosimetric studies and clinical trials.
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    Direct labeling studies of octapeptides with rhenium-188
    (R Oldenbourg Verlag, 2003-01-01) Faintuch, B. L.; Pereira, NPS; Faintuch, Salomao [UNIFESP]; Muramoto, E.; Silva, CPG; CNEN; Universidade Federal de São Paulo (UNIFESP)
    The somatostatin octapeptide lanreotide and octreotide were labeled with rhenium-188 by direct method. the optimization of the labeling, the in vitro stability of the complexes and the biodistribution were evaluated. Labeling efficiency was generally greater than 95%. the best time for reaction was 2 hours. Re-188-lanreotide gave better radiochemical yields than Re-188-octreotide, and it was stable for a longer time (24 vs. 4 hours), but the mass of lanreotide had to be larger than that for octreotide (350 vs. 250 mug), and the required ratio between mass of stannous chloride and peptide was also greater for lanreotide. Use of tartrate/phthalate buffer with Re-188-octreotide gave better radiochemical results and showed more labeling stability than the use of acetate/acetic acid buffer. the results of Cys challenge for Re-188-peptides revealed higher chelation strength for Re-188-octreotide than for Re-188-lanreotide for concentrations of cysteine below 1 mM. for a concentration of cysteine of 100 mM the rate of transchelation of Re-188 to cysteine was the same for both peptides. the CD50 value for Re-188-octreotide was 10 mM of cysteine and for Re-188-lanreotide, it was 55 mM.Re-188-labeled peptides were distributed in the gastrointestinal tract or in the kidneys and rapid blood clearance was observed in the first hour. Results indicated that the products can be obtained with high radiochemical purity, appropriate for in vivo studies to assess their efficacy in radioimmunotherapy.
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    Phytate technetium-99m versus dextran 500 technetium-99m in the sentinel lymph node biopsy
    (Taylor & Francis Ltd, 2006-02-01) Paiva, G. R.; Filho, RSO; Ferreira, L. M.; Wagner, J.; Nogueira, WSA; Novo, N. F.; Juliano, Y.; Rocha, JLBS; Universidade Federal de São Paulo (UNIFESP); Hosp Israelita Albert Einstein; Univ Santo Amaro; Univ Fec Rondonia
    Purpose: To study which of the two most used radiopharmaceutical drugs for the sentinel lymph node (SLN) biopsy procedure (dextran 500 Tc-99m and phytate Tc-99m) best defines the SLN and migrates less to other lymph nodes.Material and Methods: Thirty-two rats, separated into two groups, underwent lymphoscintigraphy examination with either dextran or phytate followed by sentinel (popliteal), lumbar, and inguinal lymph node biopsy. Radiation was detected with a gamma probe.Results: the statistical study indicated count rates significantly higher in the SLN than in the other basins for both the dextran (P < 0.01) and phytate groups (P < 0.001). There was no statistically significant difference concerning SLN absorption in either group (P=0.2981). in the dextran group, migration occurred to 1.5 lymphatic basins with counting higher than 10% of that found in the SLN versus 0.8 in the phytate group (P=0.0023). Migration was thus higher in the dextran group (P=0.0207).Conclusion: There was no statistically significant difference between dextran and phytate in the SLN identification, but the phytate migrated to fewer lymphatic basins beyond the SLN and with less intensity.