Avaliação da potencialidade do tecnécio-99m-DTPA e do tecnécio-99m-fitato de sódio, livres e encapsulados em lipossomas, na identificação de processos inflamatórios

• Ano de defesa: 2011
• Autor(a) principal: Luciene das Gracas Mota
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Lipossomas; Processos inflamatórios; Tecnécio; Tecnologia nuclear; Engenharia nuclear; Inflamação
• Link de acesso: http://hdl.handle.net/1843/MBAM-8M6QD4

The inflammatory and infectious diseases are one of the most common causes of mortality and morbidity. This paper presents the evaluation of the potential of the radiopharmaceuticals 99mTc-DTPA and 99mTc-Sodium Phytate, free and encapsulated into long-circulating and pH-sensitive (SpHL) to identify inflammatory process. Thephysicochemical characterization of freeze-dried SpHL constituted byaPEG2000-DSPE:DOPE:CHEMS (0.5:6.5:3.0 molar ratio, respectively) lyophilized in the presence of glucose as cryoprotectant at cryoprotectant:phospholipid ratio (w/w) 5:1, showed 80% of the vesicles with a diameter smaller than 350 nm, showing good homogeneity(PI=0.29). SpHL (lipid concentration of 20 mM) showed higher encapsulation efficiency, and positive zeta potential. SpHL stored in refrigerator (4°C) did not show significant changes in the mean diameter up to 180 days of storage, showing good stability. The percentage ofencapsulation of the 99mTc-DTPA in SpHL was 10.65% and 4.88% were adsorbed on the surface of the vesicles. The average diameter of SpHL-99mTc-DTPA was 207.4 ± 8.5 nm, showing good homogeneity. The SpHL radiolabeled with 99mTc-Sodium Phytate showedvesicles with mean diameter of 293.1 ± 10.4 nm and the encapsulation percentage of 14.43%. Radiopharmaceuticals 99mTc-DTPA or 99mTc- Sodium Phytate, free and encapsulated into SpHL were administered intravenously in mice-bearing inflammation focus induced by Zimosan suspension at 5% (w/v) Biodistribution studies showed significantuptake of radiolabeled SpHL in the organ of the mononuclear phagocytic system (liver and spleen). The 99mTc-DTPA, free and encapsulated, were able to identify the inflammatory focus by scintigraphic images at 2 hours post-injection. The target/ non-target ratio was greater than 1.5 for all times investigated. The data did not show statistically significantdifference between the free and encapsulated radiopharmaceuticals. The 99mTc-Sodium Phytate, free and encapsulated into SpHL also were effective to identify inflammatory process. The target/non-target ratio for 99mTc-Sodium Phytate free was higher than that obtained with SpHL-99mTc-Sodium Phytate during the entire experiment, reaching a value of 10.24 at 2 hours post-injection. These results suggesting that the 99mTc-Phytate Sodium could be employed as alternative procedure to identify inflamed.regions.