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 (¹⁹⁷Hg & ²⁰³Hg) 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.