Preparation of I-125-cytarabine and its radiochemical evaluation: Model of radio-therapeutic agent

This paper adresses the development of a new radiopharmaceutical for cancer imaging and therapy, The optimization of the labeling of thymidine analogous, cytarabine, with 1251 is described. High radiochemical yield and purity greater than or equal to98\% was obtained by reacting 50 mug cytarabine with 1251 in the presence of iodogen as oxidizing agent and 0.5M phosphate buffer of pH 7 at 65 degreesC for 30 minutes. Preliminary in-vivo study was done in nontumor bearing mice. The results revealed that this new tracer, I-125-cytarabine, has a high affinity to be localized in tissues of high proliferation rate, e.g., bone marrow greater than or equal to10\%, 60-minute post administration. Also, the labeled compound was cleared quickly from most of the body organs and concentrated in bladder greater than or equal to55\%, 60-minute post administration. These findings suggest that I-125-cytarabine, allows imaging and treatment of cancer. I-125-Cytarabine meets most of the requirements to be used as a successful diagnostic and therapeutic agent: it is a low molecular weight molecule that diffuses readily in tissues, it will not induce an antibody response, thereby leading itself to repeated injection or continuous infusion.