Tumour uptake of radiolabelled pyrimidine bases and pyrimidine nucleosides in animal models—IV. 2′- 123I-iodo-2′-deoxyuridine

Iodine-123 was produced via the 124Te( p,2 n) 123I reaction by irradiating an enriched TeO 2 target, using the DKFZ Heidelberg compact cyclotron. Radioiodine recovered from the target by sublimation was exchanged into carrier NaI, and reacted with 2,2′-anhydrouridine in dioxane and catalytic amounts of trifluoroacetic acid for 25 min at 135°C, to produce 2′- 123I-iodo-2′-deoxyruridine. Radiochemical yields were as high as 84% with specific activities estimated at 17 Ci mmol −1. Tissue distribution and excretion studies after i.v. injection of 2′ 123I-iodo-2′-deoxyuridine into Wistar rats bearing Walker 256 carcinomas indicated limited tissue uptake and rapid urinary excretion. Only thyroid, kidneys, stomach and liver accumulated radioactivity. 90% of the i.v. dose was excreted in the urine, with 39% of the dose present as unchanged 2′- 123I-iodo-2′-deoxyuridine.