Studies on F-labeled pyrimidines. Tumor uptakes of F-5-fluorouracil, F-5-fluorouridine, and F-5-fluorodeoxyuridine in animals.

Three F-labeled pyrimidines, F-5-fluorouridine (F-5-FUR), F-5-fluorouracil (F-5-FU), and F-5-fluorodeoxyuridine (F-5-FdUR), were examined regarding tissue distribution and tumor uptake in ascitic hepatoma AH109A-bearing rats. The differential absorption ratios of tumors of F-5-FUR, F-5-FU, and F-5-FdUR were 0.75±0.21, 0.92±0.15, and 0.96±0.24 at 30 min, and 0.37±0.09, 0.64±0.34, and 0.60±0.17 at 120 min, respectively. The tumor-to-organ ratios obtained with three radiopharmaceuticals, especially with blood, heart, lung, muscle, and brain were high and these ratios increased with time. The tumor-to-organ ratios obtained with F-5-FdUR were always 1.3-4 times higher than F-5-FU and F-5-FUR. We concluded that F-5-FdUR was a suitable radiopharmaceutical for tumor imaging. Positron emission tomography of a rabbit tumor located on the chest with F-5-FdUR clearly showed the tumor within 1 h. [ABSTRACT FROM AUTHOR]