DTPA

DTPA, or diethylenetriaminepentaacetic acid, is a polyaminocarboxylic acid that acts as a strong metal chelating agent. It forms stable, water-soluble complexes with many metal ions, enabling their stabilization and excretion from the body. DTPA exists as several salts, including disodium DTPA and calcium disodium DTPA, which are used in medical and diagnostic contexts. The neutral molecule features three amine groups and five carboxylate groups, a structure that underpins its high affinity for polyvalent metal ions.

In medicine and nuclear medicine, DTPA serves as a bifunctional chelator for radiometals. Technetium-99m DTPA (Tc-99m DTPA) is widely used as a radiopharmaceutical for renal imaging and for assessing renal function and glomerular filtration rate. DTPA can also chelate other radiometals for diagnostic or research purposes, forming complexes that are evaluated in imaging or therapeutic contexts.

For decorporation therapy, calcium disodium DTPA (Ca-DTPA) and zinc diethylenetriaminepentaacetate (Zn-DTPA) are used to treat internal contamination with certain radioactive materials and heavy metals, notably plutonium and americium. These agents bind the contaminants to form excretable complexes, primarily excreted via the kidneys. Ca-DTPA is commonly administered parenterally, while Zn-DTPA is often given orally or by other routes depending on the clinical scenario. The use of DTPA in chelation therapy requires medical supervision due to potential adverse effects and the risk of depleting essential metals.

Safety considerations include potential injection-site reactions, nausea, transient hypotension, and rare hypersensitivity. Monitoring and appropriate dosing are essential to minimize adverse effects.