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^99mTc(CO)₃-15-[N-(Acetyloxy)-2-picolylamino]pentadecanoic acid (1a) was prepared by incorporating [^99mTc(CO)₃]⁺ into 15-[N-(hydroxycarbonylmethyl)-2-picolylamino]pentadecanoic acid (2a). The overall radiochemical yield of 1a after HPLC purification was 60−63%. Radiotracer 1a was found to be chemically stable when incubated in human plasma for 4 h at 37 °C. Tissue distribution studies showed that high radioactivity accumulated in the heart with rapid clearance. The maximum heart-to-blood uptake ratio was 1.87 at 5 min after a tail-vein injection. Radioactive metabolites were analyzed in urine samples of mice and corresponded to a 9.3:1 ratio of ^99mTc(CO)₃-5-[N-(acetyloxy)-2-picolylamino]pentanoic acid (1b) to ^99mTc(CO)₃-3-[N-(acetyloxy)-2-picolylamino]propionic acid (1c), indicating that 1a is mainly metabolized to 1b via β-oxidation in the body. These results suggest that 1a is a promising …