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Gadopentetic acid is a gadolinium(III) complex used as a contrast agent in magnetic resonance imaging (MRI). The Gd³⁺ cation is complexed with the trianion of pentetic acid¹, also known as diethylenetriaminepentaacetic acid (DPTA).

The earliest appearance of gadopentetic acid in the chemical literature came in 1982, when Thomas J. Wenzel, Martin E. Ashley, and Robert E. Sievers* at the University of Colorado (Boulder) reported that several complexes of metal ions with polyanions could be used as water-soluble paramagnetic relaxation agents for ¹³carbon NMR spectroscopy. They found that iron(III)â€� and chromium(III)–DPTA complexes were especially suited for ; but that the gadolinium complex caused severe broadening of the carbon resonances near the complexation site because the Gd³⁺ ion bonds with other electron donors present.

Two years later, H. Gries and H. Miklautz at the Free University of Berlin disclosed that the physiochemical properties of gadopentetic acid make it a . In the ensuing years, other gadolinium-based contrast agents were investigated, including one described in 1997 by J. Platzek and co-workers at Schering (Berlin) in which Gd³⁺ is complexed with a called DO3A-butrol.

The use of gadopentetic acid in MRI has been routine since the 1990s. But in recent years, concerns arose that, despite the strength of the complex, it could break apart and enter other organs, including the brain. In February 2023, Joshua DeAguero, Brent Wagner, and collaborators at the University of New Mexico (Albuquerque) and other institutions reported that some patients who had MRI scans developed , leading to nephrogenic systemic fibrosis, a painful disease that affects the skin and organs and is often fatal. Experiments in laboratory animals confirmed this effect.

Gadolinium in the kidneys also has environmental implications. The toxic metal has been found in higher-than-normal levels in the San Francisco Bay and in tap water in New Mexico and Germany, according to the authors. Despite statements in safety data sheets that gadopentetic acid is “not a hazardous substance or mixture�, it can indeed cause considerable damage.

1. CAS Reg. No. 67-43-6.