Studies on tolonium chloride labeled with radioiodine.

Tolonium chloride is a common reagent in the diagnosis of oral premalignant and malignant lesions. This study establishes the optimal preparation of radioiodinated tolonium chloride (RTC) and evaluate its radiochemical and biological characteristics. Instant thin layer chromatography (ITLC), ion exchange chromatography (IC), paper electrophoresis, and the effect of pH on labeling efficiency revealed the chemical characterization of RTC. Biodistribution, blood clearance, urinary excretion, toxic effect, and Lugol’s solution effect on the thyroid uptake of RTC revealed RTCs biological characteristics. The optimal labeling condition was pH = 2.96 after 15 h stirring, the labeling efficiency was 60%. After purification by IC, the radiochemical purity of RTC was 94%, and the shelf life of RTC was at least 90 days. In the biodistribution study, the liver was major target organs, approximated 6.11% of injected dose accumulate in per gram of tissue (6.11% ID/g) at 10 min after injection. The tissue-to-blood radioactivity ratio significant ( p < 0.05) increased with reaction time. In liver, the tissue-to-blood radioactivity ratio was 2.2 ± 0.51 at 10 min after injection, and increased to 22.4 ± 4.52 at 120 min after injection. The blood clearance study showed a significant decrease in blood radioactivity. The radioactivity in the blood was about 2.76% of the injected dose per milliliter blood at 10 min post-injection, but decreased to 0.12% at 120 min post-injection. Lugol’s solution does not affect the thyroid uptake of RTC. Almost all the administered RTC recovered at 60 h after injection, with 79% recovered in feces and 17% recovered in urine. This study shows that RTC is non-toxic, and may be suitable as a liver imaging agent. [ABSTRACT FROM AUTHOR]