TELLURIUM-123M-LABELED 23-(ISOPROPYL TELLURO)-24-NOR-5ALPHA-CHOLAN-3BETA-OL - NEW POTENTIAL ADRENAL IMAGING AGENT

Abstract

123mTe-23-(isopropyltelluro)-24-nor-5.alpha.-cholan-3.beta.-ol (24-telluracholestanol, or 23-ITC) was prepared as a potential adrenal-imaging agent. The new agent was synthesized by the coupling of 3.beta.-acetoxy-23-bromo-24-nor-5.alpha.-cholan with 123mTe-sodium isopropyl tellurol. Tissue distribution experiments in both male and female rats indicate a high adrenal concentration of radioactivity following administration of this agent. In female rats the adrenal glands accumulated 4.5% of the injected radioactivity only 1 day after administration of 123mTe-23-ITC. The adrenal-to-liver ratio was 42 after 1 day, and this increased to 100 after 3 days. Chromatographic analyses of lipid extracts from adrenal, ovary, liver and lungs suggest that this agent is metabolized by these tissues. Examination of the rats'' excretory products indicated that .apprx. 50% of the administered radioactivity apparently is excreted in the feces within 5 days after 123mTe-23-ITC injection. The adrenals and ovaries of rats were clearly imaged with this agent, both with a rectilinear scanner and with an RC type of proportional-counter camera.