Chlormerodrin
Chlormerodrin is a mercurial diuretic commercially traded from 1952 until 1974 that was once used to treat patients with heart failure, but is no longer in widespread use. The radiolabelled form had also been used for medical imaging of the kidney and brain and the 197Hg form was even considered a contender for 99mTc by some physicians, but was ultimately discontinued by the FDA in 1989.