INVIVO STABILITY AND DISTRIBUTION OF [I-131]-LABELED IODOMETHYL TRIMETHYLAMMONIUM CHLORIDE - CONCISE COMMUNICATION

Abstract

[131I]iodomethyl trimethylammonium chloride (I-131 TMA) was prepared by the isotope-exchange reaction of diiodomethane with Na131I, followed by reaction with trimethylamine. A specific activity of 20 .mu.Ci/mg was obtained. Tissue distributions following i.v. injection of I-131 TMA in mice showed that between 10 min and 2 h, the highest accumulations of radioactivity were in the urine, kidney and heart. The uptake of this compound in the heart was very rapid and the levels of radioactivity remained fairly high up to 2 h. At 10, 30, 60 and 120 min the heart-to-blood ratios were, respectively, 10.2, 7.7, 8.3 and 9.6. Thyroid uptake of this compound in the rats and analysis of urine samples of the mouse indicated no extensive deiodination of the compound in vivo. The compound does have potential for use in myocardial imaging. Its stability in vivo makes it very useful for the radiolabeling of compounds containing quaternary ammonium moieties.