DMSA

DMSA, short for dimercaptosuccinic acid, is a chelating agent used to treat certain heavy metal poisonings and a radiopharmaceutical used in renal imaging. As a chelating agent, DMSA binds metal ions such as lead, cadmium, and mercury to form water‑soluble complexes that are excreted in urine, thereby reducing the body's heavy metal burden. A clinically used form, succimer, is administered orally and is primarily employed for pediatric lead poisoning after exposure has been controlled.

In its radiopharmaceutical form, dimercaptosuccinic acid is labeled with technetium-99m (Tc-99m DMSA) and used for renal cortical imaging. This imaging agent accumulates in the renal cortex and provides static images that help evaluate cortical integrity, renal scar formation, and congenital anomalies, particularly in children. Tc-99m DMSA imaging is commonly performed several hours after injection to assess regional renal function with relatively high cortical uptake and long retention.

Chemically, DMSA contains two thiol (sulfhydryl) groups capable of chelating metal ions. Therapeutic use relies on forming stable, water-soluble chelates that are eliminated by the kidneys. Dosing for chelation varies by guideline and patient factors; therapy is typically given in divided oral doses over multiple days or weeks under medical supervision. Safety profiles indicate that DMSA is generally well tolerated; common adverse effects include gastrointestinal upset and rash, with rare hematologic or hepatic abnormalities. It is contraindicated in certain renal impairments and in individuals with known hypersensitivity to the compound.

Regulatory status and indications differ by country, but DMSA remains a standard option in selected cases of pediatric lead poisoning and a well-established radiopharmaceutical for renal imaging.