RESUMO
OBJECTIVE: To study the influence of the 18F-FDG radioactive concentration and the usual greatest storage time of the radiopharmaceutical at the Radiopharmacy Unit (RU) over its radiochemical purity. MATERIAL AND METHODS: Thirty 18F-FDG preparations coming from different batches were studied. The radiochemical purity was determined at the RU by means of TLC to saline-diluted (1:10) and undiluted samples of each preparation, in the early 30 minutes since its arrival and 5 hours later. The radiochemical purity of the original 18F-FDG was determined at the PET radiopharmaceutical producer Laboratory (PETL) by means of HPLC in the early hour since the 18F-FDG dispensing. RESULTS: The increase of 18F-Fluoride found in the (5 h-30 min) period was significantly greater in the samples without diluting than in the diluted ones (p < 0.0001). We found a significant correlation between the percent of this increase of 18F-Fluoride (y) and the radioactive concentration of the 18F-FDG (x): y = 0.00061x + 0.1759 (R2 = 0.198; p < 0.0005). The percent of 18F-Fluoride determined at the RU was significantly higher than the percent of 18F-Fluoride determined at the PETL (p < 0.0001). A significant correlation between the differences of the percent of 18F-Fluoride determined by TLC and HPLC (y) and the radioactive concentration (x) was found: y = 0.0139x + 0.3146 (R2 = 0.196; p = 0.016). A significant correlation among the differences of percent 18F-Fluoride determined by TLC and HPLC ([%F] RU - [%F] PETL), the radioactive concentration (RC) and the time since the radiopharmaceutical dispensing (t) was found: [%F] RU - [%F] PETL = 0.01159*RC (mCi/mL) + 0.250*t (h) - 0.01903 (R2 = 0.226; p < 0.014). CONCLUSIONS: The stability of the 18F-FDG preparations with time increases when diminishing its concentration. We recommended the dilution of these preparations with physiological saline solution.
Assuntos
Fluordesoxiglucose F18/química , Acetilação , Cromatografia Líquida de Alta Pressão , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Radioisótopos de Flúor/análise , Radioatividade , Fatores de TempoRESUMO
Objetivo. Determinar la influencia de la concentración radiactiva de la 2-[ 18F]-fluoro-2-desoxi-D-glucosa ( 18F-FDG) y el tiempo de almacenamiento máximo habitual del radiofármaco en la Unidad de Radiofarmacia (UR) sobre su pureza radioquímica. Material y métodos. Se estudiaron 30 preparaciones de 18F-FDG procedentes de lotes diferentes. Se determinó la pureza radioquímica en la UR dentro de los 30 minutos siguientes a su recepción y a las 5 horas mediante cromatografía en capa fina (TLC) a las muestras diluidas con suero salino fisiológico (1:10) y sin diluir. La pureza radioquímica también se determinó en el Laboratorio de radiofármacos PET (LPET) dentro de la primera hora posterior a su dispensación por cromatografía líquida a alta presión (HPLC). Resultados. El aumento de porcentaje de 18F-Fluoruro a las 5 horas fue significativamente mayor en las muestras sin diluir que en las diluidas (p < 0,0001), encontrándose una correlación significativa entre el aumento de porcentaje de 18F-Fluoruro con el tiempo (y) respecto a la concentración radiactiva (x): y = 0,0061x + 0,1759 (R 2 = 0,1977; p < 0,0005). El porcentaje de 18F-Fluoruro determinado en la UR fue significativamente mayor que el determinado en el LPET (p < 0,0001), obteniéndose una correlación significativa entre el aumento de porcentaje de 18F-Fluoruro (y) y la concentración radiactiva (x): y = 0,0139x + 0,3146 (R 2 = 0,196; p = 0,016). Se obtuvo una correlación significativa entre este aumento ([ %F] UR [ %F] LPET), la concentración radiactiva (CR) y el tiempo desde la dispensación (t): [ %F] UR [ %F] LPET = 0,01159*CR (mCi/ml) + 0,250*t (h) 0,01903 (R 2 = 0,226; p = 0,014). Conclusiones. La estabilidad de las preparaciones de 18F-FDG aumenta al disminuir su concentración. Aconsejamos la dilución de estas preparaciones con solución salina fisiológica
Objective. To study the influence of the 18F-FDG radioactive concentration and the usual greatest storage time of the radiopharmaceutical at the Radiopharmacy Unit (RU) over its radiochemical purity. Material and methods. Thirty 18F-FDG preparations coming from different batches were studied. The radiochemical purity was determined at the RU by means of TLC to saline-diluted (1:10) and undiluted samples of each preparation, in the early 30 minutes since its arrival and 5 hours later. The radiochemical purity of the original 18F-FDG was determined at the PET radiopharmaceutical producer Laboratory (PETL) by means of HPLC in the early hour since the 18F-FDG dispensing. Results. The increase of 18F-Fluoride found in the (5 h-30 min) period was significantly greater in the samples without diluting than in the diluted ones (p < 0,0001). We found a significant correlation between the percent of this increase of 18F-Fluoride (y) and the radioactive concentration of the 18F-FDG (x): y = 0,00061x + 0,1759 (R 2 = 0,198; p < 0,0005). The percent of 18F-Fluoride determined at the RU was significantly higher than the percent of 18F-Fluoride determined at the PETL (p < 0,0001). A significant correlation between the differences of the percent of 18F-Fluoride determined by TLC and HPLC (y) and the radioactive concentration (x) was found: y = 0,0139x + 0,3146 (R 2 = 0,196; p = 0,016). A significant correlation among the differences of percent 18F-Fluoride determined by TLC and HPLC ([ %F] RU [ %F] PETL), the radioactive concentration (RC) and the time since the radiopharmaceutical dispensing (t) was found: [ %F] RU [ %F] PETL = 0,01159*RC (mCi/mL) + 0,250*t (h) 0,01903 (R 2 = 0,226; p < 0,014). Conclusions. The stability of the 18F-FDG preparations with time increases when diminishing its concentration. We recommended the dilution of these preparations with physiological saline solution
